diff --git a/DailyQuest/DailyQuest/Data/PersistentStorages/BrowseQuestsStorage/BrowseQuestsStorage.swift b/DailyQuest/DailyQuest/Data/PersistentStorages/BrowseQuestsStorage/BrowseQuestsStorage.swift
index 200ce08..9ac2a7c 100644
--- a/DailyQuest/DailyQuest/Data/PersistentStorages/BrowseQuestsStorage/BrowseQuestsStorage.swift
+++ b/DailyQuest/DailyQuest/Data/PersistentStorages/BrowseQuestsStorage/BrowseQuestsStorage.swift
@@ -8,7 +8,7 @@
 import RxSwift
 
 protocol BrowseQuestsStorage {
-    func fetchBrowseQuests() -> Observable<[BrowseQuest]>
+    func fetchBrowseQuests() -> Single<[BrowseQuest]>
     func saveBrowseQuest(browseQuest: BrowseQuest) -> Single<BrowseQuest>
     func deleteBrowseQuests() -> Single<Bool>
 }
diff --git a/DailyQuest/DailyQuest/Data/PersistentStorages/BrowseQuestsStorage/RealmStorage/RealmBrowseQuestsStorage.swift b/DailyQuest/DailyQuest/Data/PersistentStorages/BrowseQuestsStorage/RealmStorage/RealmBrowseQuestsStorage.swift
index be722a2..e5b8e51 100644
--- a/DailyQuest/DailyQuest/Data/PersistentStorages/BrowseQuestsStorage/RealmStorage/RealmBrowseQuestsStorage.swift
+++ b/DailyQuest/DailyQuest/Data/PersistentStorages/BrowseQuestsStorage/RealmStorage/RealmBrowseQuestsStorage.swift
@@ -17,8 +17,8 @@ final class RealmBrowseQuestsStorage {
 }
 
 extension RealmBrowseQuestsStorage: BrowseQuestsStorage {
-    func fetchBrowseQuests() -> Observable<[BrowseQuest]> {
-        return Observable<[BrowseQuest]>.create { [weak self] observer in
+    func fetchBrowseQuests() -> Single<[BrowseQuest]> {
+        return Single<[BrowseQuest]>.create { [weak self] single in
             guard let realmStorage = self?.realmStorage else {
                 return Disposables.create()
             }
@@ -26,10 +26,9 @@ extension RealmBrowseQuestsStorage: BrowseQuestsStorage {
             do {
                 let browseQuests = try realmStorage.fetchEntities(type: BrowseQuestEntity.self)
                     .compactMap { $0.toDomain() }
-                observer.onNext(browseQuests)
-                observer.onCompleted()
+                single(.success(browseQuests))
             } catch let error {
-                observer.onError(error)
+                single(.failure(error))
             }
 
             return Disposables.create()
diff --git a/DailyQuest/DailyQuest/Data/PersistentStorages/UserInfoStorage/RealmStorage/RealmUserInfoStorage.swift b/DailyQuest/DailyQuest/Data/PersistentStorages/UserInfoStorage/RealmStorage/RealmUserInfoStorage.swift
index 6150932..090fab5 100644
--- a/DailyQuest/DailyQuest/Data/PersistentStorages/UserInfoStorage/RealmStorage/RealmUserInfoStorage.swift
+++ b/DailyQuest/DailyQuest/Data/PersistentStorages/UserInfoStorage/RealmStorage/RealmUserInfoStorage.swift
@@ -17,40 +17,27 @@ final class RealmUserInfoStorage {
 }
 
 extension RealmUserInfoStorage: UserInfoStorage {
-    func fetchUserInfo() -> Observable<User> {
-        return Observable<User>.create { [weak self] observer in
-            guard let realmStorage = self?.realmStorage else {
-                // self가 존재하지 않을 경우, 반환하지 않고 종료
-                return Disposables.create()
-            }
-
+    func fetchUserInfo() -> Single<User> {
+        return Single<User>.create { [weak self] single in
             do {
+                guard let realmStorage = self?.realmStorage else { throw RealmStorageError.realmObjectError }
                 guard let userInfoEntity = try realmStorage.fetchEntities(type: UserInfoEntity.self)
                     .first else {
                     throw RealmStorageError.noDataError
                 }
-
-                observer.onNext(userInfoEntity.toDomain())
-                observer.onCompleted()
+                single(.success(userInfoEntity.toDomain()))
             } catch let error {
-                // Realm을 불러올 수 없을 경우, realmObjectError
-                // User 정보가 없을 경우, noDataError
-                observer.onError(error)
+                single(.failure(error))
             }
-
             return Disposables.create()
         }
     }
 
     func updateUserInfo(user: User) -> Single<User> {
         return Single.create { [weak self] single in
-            guard let realmStorage = self?.realmStorage else {
-                return Disposables.create()
-            }
-
             let userInfo = UserInfoEntity(user: user)
-
             do {
+                guard let realmStorage = self?.realmStorage else { throw RealmStorageError.realmObjectError }
                 // update 성공했을 경우, success(user)
                 try realmStorage.updateEntity(entity: userInfo)
                 single(.success(user))
@@ -65,12 +52,8 @@ extension RealmUserInfoStorage: UserInfoStorage {
 
     func deleteUserInfo() -> Single<User> {
         return Single.create { [weak self] single in
-            guard let realmStorage = self?.realmStorage else {
-                return Disposables.create()
-            }
-
             do {
-                // update 성공했을 경우, success(user)
+                guard let realmStorage = self?.realmStorage else { throw RealmStorageError.realmObjectError }
                 guard let user = try realmStorage.deleteAllEntity(type: UserInfoEntity.self).first?.toDomain() else {
                     throw RealmStorageError.noDataError
                 }
@@ -79,7 +62,6 @@ extension RealmUserInfoStorage: UserInfoStorage {
                 // update 성공하지 못했을 경우, failure(error)
                 single(.failure(RealmStorageError.deleteError(error)))
             }
-
             return Disposables.create()
         }
     }
diff --git a/DailyQuest/DailyQuest/Data/PersistentStorages/UserInfoStorage/UserInfoStorage.swift b/DailyQuest/DailyQuest/Data/PersistentStorages/UserInfoStorage/UserInfoStorage.swift
index 3b67cc1..4ec6586 100644
--- a/DailyQuest/DailyQuest/Data/PersistentStorages/UserInfoStorage/UserInfoStorage.swift
+++ b/DailyQuest/DailyQuest/Data/PersistentStorages/UserInfoStorage/UserInfoStorage.swift
@@ -8,7 +8,7 @@
 import RxSwift
 
 protocol UserInfoStorage {
-    func fetchUserInfo() -> Observable<User>
+    func fetchUserInfo() -> Single<User>
     func updateUserInfo(user: User) -> Single<User>
     func deleteUserInfo() -> Single<User>
 }
diff --git a/DailyQuest/DailyQuest/Data/Repositories/DefaultBrowseRepository.swift b/DailyQuest/DailyQuest/Data/Repositories/DefaultBrowseRepository.swift
index 07c1a18..6bed6e4 100644
--- a/DailyQuest/DailyQuest/Data/Repositories/DefaultBrowseRepository.swift
+++ b/DailyQuest/DailyQuest/Data/Repositories/DefaultBrowseRepository.swift
@@ -26,14 +26,14 @@ extension DefaultBrowseRepository: BrowseRepository {
     /// Fetch BrowseQuests
     /// Firebase 우선, 실패시 persistentStorage, persistentStorage도 실패시 Error반환
     /// - Returns: Observable<[BrowseQuest]>
-    func fetch() -> Observable<[BrowseQuest]> {
-        return self.networkService.getAllowUsers(limit: 10)
+    func fetch() -> Single<[BrowseQuest]> {
+        let uid = networkService.uid.value
+        return networkService.getAllowUsers(limit: 10)
             .map { $0.toDomain() }
             .flatMap(fetchBrowseQuestNetworkService(user:))
-            .filter { !$0.quests.isEmpty }
+            .filter { !$0.quests.isEmpty &&  uid != $0.user.uuid }
             .toArray()
-            .asObservable()
-            .do(afterNext: { [weak self] browseQuests in
+            .do(afterSuccess: { [weak self] browseQuests in
             guard let self = self else { return }
             self.persistentStorage.deleteBrowseQuests()
                 .asObservable()
@@ -45,20 +45,20 @@ extension DefaultBrowseRepository: BrowseRepository {
                 .disposed(by: self.disposeBag)
         })
             .timeout(.seconds(5), scheduler: MainScheduler.instance)
-            .catch { _ in
-            return self.persistentStorage.fetchBrowseQuests()
+            .catch { [weak self] _ in
+                guard let self = self else { return Single.just([])}
+                return self.persistentStorage.fetchBrowseQuests()
         }
     }
 }
 
 private extension DefaultBrowseRepository {
-    func fetchBrowseQuestNetworkService(user: User) -> Observable<BrowseQuest> {
+    func fetchBrowseQuestNetworkService(user: User) -> Single<BrowseQuest> {
         networkService
             .read(type: QuestDTO.self, userCase: .anotherUser(user.uuid), access: .quests, filter: .today(Date()))
             .map { $0.toDomain() }
             .toArray()
-            .asObservable()
-            .map { return BrowseQuest(user: user, quests: $0) }
+            .map { BrowseQuest(user: user, quests: $0) }
     }
 
     func saveBrowseQuestPersistentStorage(browseQuest: BrowseQuest) -> Observable<BrowseQuest> {
diff --git a/DailyQuest/DailyQuest/Data/Repositories/DefaultQuestsRepository.swift b/DailyQuest/DailyQuest/Data/Repositories/DefaultQuestsRepository.swift
index 73df3ba..fb18ece 100644
--- a/DailyQuest/DailyQuest/Data/Repositories/DefaultQuestsRepository.swift
+++ b/DailyQuest/DailyQuest/Data/Repositories/DefaultQuestsRepository.swift
@@ -24,11 +24,10 @@ extension DefaultQuestsRepository: QuestsRepository {
             .flatMap (saveNetworkService(quests:))
     }
     
-    func fetch(by date: Date) -> Observable<[Quest]> {
+    func fetch(by date: Date) -> Single<[Quest]> {
         return persistentStorage.fetchQuests(by: date)
-            .asObservable()
             .catch { [weak self] _ in
-                guard let self = self else { return Observable.just([]) }
+                guard let self = self else { return Single.just([]) }
                 return self.fetchNetworkService(date: date)
             }
             .catchAndReturn([])
@@ -49,14 +48,13 @@ extension DefaultQuestsRepository: QuestsRepository {
             .flatMap(deleteAllNetworkService(quests:))
     }
     
-    func fetch(by uuid: String, date: Date) -> Observable<[Quest]> {
+    func fetch(by uuid: String, date: Date) -> Single<[Quest]> {
         return networkService.read(type: QuestDTO.self,
                                    userCase: .anotherUser(uuid),
                                    access: .quests,
                                    filter: .today(date))
         .map { $0.toDomain() }
         .toArray()
-        .asObservable()
     }
 }
 
@@ -74,11 +72,10 @@ private extension DefaultQuestsRepository {
             .toArray()
     }
     
-    func fetchNetworkService(date: Date) -> Observable<[Quest]> {
+    func fetchNetworkService(date: Date) -> Single<[Quest]> {
         return networkService.read(type: QuestDTO.self, userCase: .currentUser, access: .quests, filter: .today(date))
             .map { $0.toDomain() }
             .toArray()
-            .asObservable()
             .catchAndReturn([])
     }
     
diff --git a/DailyQuest/DailyQuest/Data/Repositories/DefaultUserRepository.swift b/DailyQuest/DailyQuest/Data/Repositories/DefaultUserRepository.swift
index 2114a69..64582a9 100644
--- a/DailyQuest/DailyQuest/Data/Repositories/DefaultUserRepository.swift
+++ b/DailyQuest/DailyQuest/Data/Repositories/DefaultUserRepository.swift
@@ -30,17 +30,14 @@ extension DefaultUserRepository: UserRepository {
     func readUser() -> Single<User> {
         return self.persistentStorage.fetchUserInfo()
             .catch { [weak self] _ in
-                guard let self = self else { return Observable.just(User()) }
+                guard let self = self else { return Single.just(User()) }
                 return self.fetchUserNetworkService()
             }
-            .asSingle()
     }
     
     func updateUser(by user: User) -> Single<User> {
         return persistentStorage.updateUserInfo(user: user)
-            .asObservable()
             .flatMap(updateUserNetworkService(user:))
-            .asSingle()
     }
     
     func fetchUser(by uuid: String) -> Single<User> {
@@ -67,13 +64,12 @@ extension DefaultUserRepository: UserRepository {
                         return self.networkService.update(userCase: .currentUser, access: .userInfo, dto: userDto)
                     }
                     .map { $0.toDomain() }
-                    .asSingle()
             }
             .flatMap(updateUser(by:))
             .map { _ in true }
             .catchAndReturn(false)
-            .do(afterSuccess: { _ in
-                NotificationCenter.default.post(name: .userUpdated, object: nil)
+            .do(afterSuccess: { result in
+                NotificationCenter.default.post(name: .userUpdated, object: result)
             })
     }
     
@@ -92,7 +88,6 @@ extension DefaultUserRepository: UserRepository {
                         return self.networkService.update(userCase: .currentUser, access: .userInfo, dto: userDto)
                     }
                     .map { $0.toDomain() }
-                    .asSingle()
             }
             .flatMap(updateUser(by:))
             .map { _ in true }
@@ -105,11 +100,11 @@ extension DefaultUserRepository: UserRepository {
 }
 
 extension DefaultUserRepository: ProtectedUserRepository {
-    func deleteUser() -> Observable<Bool> {
+    func deleteUser() -> Single<Bool> {
         return networkService
             .delete(userCase: .currentUser, access: .userInfo, dto: UserDTO())
             .flatMap { [weak self] _ in
-                guard let self = self else { return .just(true) }
+                guard let self = self else { return .just(false) }
                 return self.networkService.deleteUser()
                     .flatMap { _ in
                         return self.persistentStorage.deleteUserInfo()
@@ -117,8 +112,7 @@ extension DefaultUserRepository: ProtectedUserRepository {
                     }
             }
             .catchAndReturn(false)
-            .asObservable()
-            .do(onNext: { [weak self]_ in
+            .do(onSuccess: { [weak self]_ in
                 guard let self = self else { return }
                 self.networkService.signOut().subscribe()
                     .disposed(by: self.disposeBag)
@@ -127,15 +121,15 @@ extension DefaultUserRepository: ProtectedUserRepository {
 }
 
 private extension DefaultUserRepository {
-    func fetchUserNetworkService() -> Observable<User> {
+    func fetchUserNetworkService() -> Single<User> {
         networkService.read(type: UserDTO.self, userCase: .currentUser, access: .userInfo, filter: nil)
             .map { $0.toDomain() }
+            .asSingle()
     }
     
-    func updateUserNetworkService(user: User) -> Observable<User> {
+    func updateUserNetworkService(user: User) -> Single<User> {
         networkService.update(userCase: .currentUser, access: .userInfo, dto: user.toDTO())
             .map { $0.toDomain() }
-            .asObservable()
             .catchAndReturn(user)
     }
 }
diff --git a/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/BrowseRepository.swift b/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/BrowseRepository.swift
index 1ae7940..bf1ccef 100644
--- a/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/BrowseRepository.swift
+++ b/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/BrowseRepository.swift
@@ -9,5 +9,5 @@ import RxSwift
 
 protocol BrowseRepository {
     // TODO: 무한 스크롤을 위한 페이징 추가
-    func fetch() -> Observable<[BrowseQuest]>
+    func fetch() -> Single<[BrowseQuest]>
 }
diff --git a/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/ProtectedUserRepository.swift b/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/ProtectedUserRepository.swift
index cf438e2..9cc02f5 100644
--- a/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/ProtectedUserRepository.swift
+++ b/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/ProtectedUserRepository.swift
@@ -10,5 +10,5 @@ import RxSwift
 protocol ProtectedUserRepository {
     /// 유저정보를 삭제합니다.
     /// - Returns: 삭제 성공 여부를 방출하는 Observable입니다.
-    func deleteUser() -> Observable<Bool>
+    func deleteUser() -> Single<Bool>
 }
diff --git a/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/QuestsRepository.swift b/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/QuestsRepository.swift
index b8a82db..5031d10 100644
--- a/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/QuestsRepository.swift
+++ b/DailyQuest/DailyQuest/Domain/Interfaces/Repositories/QuestsRepository.swift
@@ -26,7 +26,7 @@ protocol QuestsRepository {
         - date: 받아오길 원하는 날짜입니다.
      - Returns: Quest의 배열을 방출하는 Observable입니다. 비어있다면 비어있는 배열을 방출합니다.
      */
-    func fetch(by date: Date) -> Observable<[Quest]>
+    func fetch(by date: Date) -> Single<[Quest]>
 
     /**
      해당 날짜의 퀘스트 값(`currentCount`)을 업데이트 합니다.
@@ -56,5 +56,5 @@ protocol QuestsRepository {
      */
     func deleteAll(with groupId: UUID) -> Single<[Quest]>
 
-    func fetch(by uuid: String, date: Date) -> Observable<[Quest]>
+    func fetch(by uuid: String, date: Date) -> Single<[Quest]>
 }
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Browse/DefaultBrowseUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Browse/DefaultBrowseUseCase.swift
index f6bfeba..a7c886c 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Browse/DefaultBrowseUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Browse/DefaultBrowseUseCase.swift
@@ -18,13 +18,13 @@ final class DefaultBrowseUseCase {
 }
 
 extension DefaultBrowseUseCase: BrowseUseCase {
-    func excute() -> Observable<[BrowseQuest]> {
+    func excute() -> Single<[BrowseQuest]> {
         return browseRepository.fetch()
     }
 }
 
 final class BrowseMockRepo: BrowseRepository {
-    func fetch() -> RxSwift.Observable<[BrowseQuest]> {
+    func fetch() -> Single<[BrowseQuest]> {
         return .just([BrowseQuest(user: User(uuid: "", nickName: "test", profileURL: "", backgroundImageURL: "", introduce: "", allow: false), quests: [])])
     }
 }
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Browse/Protocols/BrowseUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Browse/Protocols/BrowseUseCase.swift
index 4cbbe16..66f0b6d 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Browse/Protocols/BrowseUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Browse/Protocols/BrowseUseCase.swift
@@ -10,5 +10,5 @@ import Foundation
 import RxSwift
 
 protocol BrowseUseCase {
-    func excute() -> Observable<[BrowseQuest]>
+    func excute() -> Single<[BrowseQuest]>
 }
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Common/DefaultFriendCalendarUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Common/DefaultFriendCalendarUseCase.swift
index 200d439..59d1c28 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Common/DefaultFriendCalendarUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Common/DefaultFriendCalendarUseCase.swift
@@ -68,6 +68,7 @@ extension DefaultFriendCalendarUseCase {
                 
                 return self.questsRepository
                     .fetch(by: self.user.uuid, date: date)
+                    .asObservable()
                     .map { quests -> DailyQuestCompletion in
                         let isSelected = (try? self.selectedDate.value().startOfDay == date) ?? false
                         
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Common/DefaultFriendQuestUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Common/DefaultFriendQuestUseCase.swift
index dd38790..a95e69e 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Common/DefaultFriendQuestUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Common/DefaultFriendQuestUseCase.swift
@@ -18,7 +18,7 @@ final class DefaultFriendUseCase {
 }
 
 extension DefaultFriendUseCase: FriendQuestUseCase {
-    func fetch(with uuid: String, by date: Date) -> Observable<[Quest]> {
+    func fetch(with uuid: String, by date: Date) -> Single<[Quest]> {
         return questsRepository.fetch(by: uuid, date: date)
     }
 }
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Common/Protocols/FriendQuestUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Common/Protocols/FriendQuestUseCase.swift
index a8d8ce8..f522859 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Common/Protocols/FriendQuestUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Common/Protocols/FriendQuestUseCase.swift
@@ -10,5 +10,5 @@ import Foundation
 import RxSwift
 
 protocol FriendQuestUseCase {
-    func fetch(with uuid: String, by date: Date) -> Observable<[Quest]>
+    func fetch(with uuid: String, by date: Date) -> Single<[Quest]>
 }
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultEnrollUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultEnrollUseCase.swift
index 0fffba6..b34d248 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultEnrollUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultEnrollUseCase.swift
@@ -18,7 +18,7 @@ final class DefaultEnrollUseCase {
 }
 
 extension DefaultEnrollUseCase: EnrollUseCase {
-    func save(with quests: [Quest]) -> Observable<Bool> {
+    func save(with quests: [Quest]) -> Single<Bool> {
         return questsRepository
             .save(with: quests)
             .map { _ in
@@ -29,6 +29,5 @@ extension DefaultEnrollUseCase: EnrollUseCase {
                 let dates = quests.map { $0.date }
                 NotificationCenter.default.post(name: .updated, object: dates)
             })
-            .asObservable()
     }
 }
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultQuestUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultQuestUseCase.swift
index 974e063..5879606 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultQuestUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultQuestUseCase.swift
@@ -18,11 +18,11 @@ final class DefaultQuestUseCase {
 }
 
 extension DefaultQuestUseCase: QuestUseCase {
-    func fetch(by date: Date) -> Observable<[Quest]> {
+    func fetch(by date: Date) -> Single<[Quest]> {
         return questsRepository.fetch(by: date)
     }
     
-    func update(with quest: Quest) -> Observable<Bool> {
+    func update(with quest: Quest) -> Single<Bool> {
         return questsRepository
             .update(with: quest)
             .do(onSuccess: { quest in
@@ -32,6 +32,5 @@ extension DefaultQuestUseCase: QuestUseCase {
             })
             .map { _ in true }
             .catchAndReturn(false)
-            .asObservable()
     }
 }
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultUserUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultUserUseCase.swift
index 4a5346d..886375f 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultUserUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Home/DefaultUserUseCase.swift
@@ -27,36 +27,31 @@ extension DefaultUserUseCase: UserUseCase {
             .asObservable()
     }
     
-    func fetch() -> Observable<User> {
+    func fetch() -> Single<User> {
         return userRepository.readUser()
             .catchAndReturn(User())
-            .asObservable()
             
     }
     
-    func save(with user: User) -> Observable<User> {
+    func save(with user: User) -> Single<User> {
         return userRepository.updateUser(by: user)
             .catchAndReturn(User())
-            .asObservable()
     }
     
-    func saveProfileImage(data: Data) -> Observable<Bool> {
+    func saveProfileImage(data: Data) -> Single<Bool> {
         return userRepository.saveProfileImage(data: data)
             .catchAndReturn(false)
-            .asObservable()
     }
     
-    func saveBackgroundImage(data: Data) -> Observable<Bool> {
+    func saveBackgroundImage(data: Data) -> Single<Bool> {
         return userRepository.saveBackgroundImage(data: data)
             .catchAndReturn(false)
-            .asObservable()
     }
 
-    func delete() -> Observable<Bool> {
-        guard let userRepository = userRepository as? ProtectedUserRepository else { return Observable.just(false) }
+    func delete() -> Single<Bool> {
+        guard let userRepository = userRepository as? ProtectedUserRepository else { return Single.just(false) }
         return userRepository.deleteUser()
             .catchAndReturn(false)
-            .asObservable()
     }
 }
 
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Home/HomeCalendarUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Home/HomeCalendarUseCase.swift
index 04fd2da..d3975f0 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Home/HomeCalendarUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Home/HomeCalendarUseCase.swift
@@ -148,6 +148,7 @@ extension HomeCalendarUseCase {
                 
                 return self.questsRepository
                     .fetch(by: date)
+                    .asObservable()
                     .map { quests -> DailyQuestCompletion in
                         let isSelected = (try? self.selectedDate.value().startOfDay == date) ?? false
                         
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/EnrollUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/EnrollUseCase.swift
index 32f4db4..2e91122 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/EnrollUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/EnrollUseCase.swift
@@ -10,5 +10,5 @@ import Foundation
 import RxSwift
 
 protocol EnrollUseCase {
-    func save(with quests: [Quest]) -> Observable<Bool>
+    func save(with quests: [Quest]) -> Single<Bool>
 }
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/QuestUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/QuestUseCase.swift
index 4d88349..94e5ae9 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/QuestUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/QuestUseCase.swift
@@ -10,6 +10,6 @@ import Foundation
 import RxSwift
 
 protocol QuestUseCase {
-    func fetch(by date: Date) -> Observable<[Quest]>
-    func update(with quest: Quest) -> Observable<Bool>
+    func fetch(by date: Date) -> Single<[Quest]>
+    func update(with quest: Quest) -> Single<Bool>
 }
diff --git a/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/UserUseCase.swift b/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/UserUseCase.swift
index 138ccc9..ab9007d 100644
--- a/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/UserUseCase.swift
+++ b/DailyQuest/DailyQuest/Domain/UseCases/Home/Protocols/UserUseCase.swift
@@ -10,11 +10,11 @@ import RxSwift
 
 protocol UserUseCase {
     func isLoggedIn() -> Observable<Bool>
-    func fetch() -> Observable<User>
-    func save(with user: User) -> Observable<User>
+    func fetch() -> Single<User>
+    func save(with user: User) -> Single<User>
     
-    func saveProfileImage(data: Data) -> Observable<Bool>
-    func saveBackgroundImage(data: Data) -> Observable<Bool>
+    func saveProfileImage(data: Data) -> Single<Bool>
+    func saveBackgroundImage(data: Data) -> Single<Bool>
     
-    func delete() -> Observable<Bool>
+    func delete() -> Single<Bool>
 }
diff --git a/DailyQuest/DailyQuest/Presentation/Common/ViewModel/FriendViewModel.swift b/DailyQuest/DailyQuest/Presentation/Common/ViewModel/FriendViewModel.swift
index b934e0b..8975ed7 100644
--- a/DailyQuest/DailyQuest/Presentation/Common/ViewModel/FriendViewModel.swift
+++ b/DailyQuest/DailyQuest/Presentation/Common/ViewModel/FriendViewModel.swift
@@ -78,5 +78,6 @@ final class FriendViewModel {
 private extension FriendViewModel {
     func fetch(by date: Date) -> Observable<[Quest]> {
         return friendQuestUseCase.fetch(with: user.uuid, by: date)
+            .asObservable()
     }
 }
diff --git a/DailyQuest/DailyQuest/Presentation/Home/ViewModel/ProfileViewModel.swift b/DailyQuest/DailyQuest/Presentation/Home/ViewModel/ProfileViewModel.swift
index 840ccb2..aae8f52 100644
--- a/DailyQuest/DailyQuest/Presentation/Home/ViewModel/ProfileViewModel.swift
+++ b/DailyQuest/DailyQuest/Presentation/Home/ViewModel/ProfileViewModel.swift
@@ -56,6 +56,7 @@ final class ProfileViewModel {
             return self.userUseCase.saveProfileImage(data: data)
                 .map{ _ in image }
                 .catchAndReturn(nil)
+                .asObservable()
         }.map{ _ in
             Void()
         }.flatMap(userUseCase.fetch)