diff --git a/Projects/Domain/PomodoroService/Sources/PomodoroService.swift b/Projects/Domain/PomodoroService/Sources/PomodoroService.swift
index c07e059..179b44f 100644
--- a/Projects/Domain/PomodoroService/Sources/PomodoroService.swift
+++ b/Projects/Domain/PomodoroService/Sources/PomodoroService.swift
@@ -18,8 +18,6 @@ extension PomodoroService: DependencyKey {
   public static let liveValue: PomodoroService = .live()
   
   private static func live() -> PomodoroService {
-    
-    
     return .init(
       syncCategoryList: {
         apiClient, databaseClient in
@@ -60,20 +58,13 @@ extension PomodoroService: DependencyKey {
           identifier: "com.pomonyang.mohanyang.update_LiveActivity",
           queue: nil
         ) { task in
-          print("BackgroundTask 호출!!")
           task.expirationHandler = {
-            print("BackgroundTask 끝!!")
             task.setTaskCompleted(success: false)
           }
-          
           let pomodoroActivities = liveActivityClient.protocolAdapter.getActivities(type: PomodoroActivityAttributes.self)
           Task {
-            for activity in pomodoroActivities {
-              await liveActivityClient.protocolAdapter.updateActivity(
-                type(of: activity.attributes),
-                id: activity.id,
-                content: activity.content
-              )
+            if let firstActivity = pomodoroActivities.first {
+              await firstActivity.update(firstActivity.content)
             }
             task.setTaskCompleted(success: true)
           }
diff --git a/Projects/Feature/Feature/Sources/AppCore.swift b/Projects/Feature/Feature/Sources/AppCore.swift
index 881661e..a6c204d 100644
--- a/Projects/Feature/Feature/Sources/AppCore.swift
+++ b/Projects/Feature/Feature/Sources/AppCore.swift
@@ -19,9 +19,11 @@ import UserDefaultsClientInterface
 import UserNotificationClientInterface
 import CatServiceInterface
 import UserServiceInterface
+import PomodoroServiceInterface
 import DatabaseClientInterface
 import StreamListenerInterface
 import BackgroundTaskClientInterface
+import LiveActivityClientInterface
 
 import ComposableArchitecture
 
@@ -37,9 +39,9 @@ public struct AppCore {
     var onboarding: OnboardingCore.State?
     @Presents var networkError: NetworkErrorCore.State?
     @Presents var requestError: RequestErrorCore.State?
-
+    
     var isLoading: Bool = false
-
+    
     public init() {}
   }
   
@@ -62,7 +64,8 @@ public struct AppCore {
   @Dependency(DatabaseClient.self) var databaseClient
   @Dependency(StreamListener.self) var streamListener
   @Dependency(BackgroundTaskClient.self) var backgroundTaskClient
-
+  @Dependency(LiveActivityClient.self) var liveActivityClient
+  
   public init() {}
   
   public var body: some ReducerOf<Self> {
@@ -101,56 +104,62 @@ public struct AppCore {
           await send(.serverState(serverState))
         }
       }
-
+      
     case .appDelegate:
       return .none
       
     case .didChangeScenePhase(.background):
-      let request = BGAppRefreshTaskRequest(identifier: "com.pomonyang.mohanyang.update_LiveActivity")
-      request.earliestBeginDate = Date(timeIntervalSinceNow: 60)
-      
-      
-      do {
-        try BGTaskScheduler.shared.submit(request)
-      } catch {
-        print("BGTaskScheduler not submitted")
-      }
       return .run { send in
-        // 현재 타이머가 실행중이면 submit 해야함
-        //
+        let pomodoroActivity = liveActivityClient.protocolAdapter.getActivities(type: PomodoroActivityAttributes.self).first
+        let pendingBGTaskRequest = await backgroundTaskClient.pendingTaskRequests().first
         
+        if let pomodoroActivity {
+          if let pendingBGTaskRequest {
+            if pendingBGTaskRequest.earliestBeginDate != pomodoroActivity.content.state.goalDatetime {
+              backgroundTaskClient.cancel(identifier: pendingBGTaskRequest.identifier)
+              await pomodoroActivity.update(pomodoroActivity.content)
+              try submitUpdateLiveActivityBGTask(earliestBeginDate: pomodoroActivity.content.state.goalDatetime)
+            }
+          } else {
+            try submitUpdateLiveActivityBGTask(earliestBeginDate: pomodoroActivity.content.state.goalDatetime)
+          }
+        } else {
+          if let pendingBGTaskRequest {
+            backgroundTaskClient.cancel(identifier: pendingBGTaskRequest.identifier)
+          }
+        }
       }
       
     case .didChangeScenePhase:
       return .none
-
+      
     case .splash(.moveToHome):
       state.splash = nil
       state.home = HomeCore.State()
       return .none
-
+      
     case .splash(.moveToOnboarding):
       state.splash = nil
       state.onboarding = OnboardingCore.State()
       return .none
-
+      
     case .splash:
       return .none
-
+      
     case .home:
       return .none
-
+      
     case .onboarding(.selectCat(.presented(.namingCat(.presented(.moveToHome))))):
       state.onboarding = nil
       state.home = HomeCore.State()
       return .none
-
+      
     case .onboarding:
       return .none
-
+      
     case .networkError:
       return .none
-
+      
     case .requestError(.presented(.moveToHome)):
       if state.onboarding != nil {
         state.onboarding = OnboardingCore.State()
@@ -158,10 +167,10 @@ public struct AppCore {
         state.home = HomeCore.State()
       }
       return .none
-
+      
     case .requestError:
       return .none
-
+      
     case .serverState(let serverState):
       switch serverState {
       case .requestStarted:
@@ -178,4 +187,12 @@ public struct AppCore {
       return .none
     }
   }
+  
+  func submitUpdateLiveActivityBGTask(earliestBeginDate: Date) throws {
+    let request = BGProcessingTaskRequest(identifier: "com.pomonyang.mohanyang.update_LiveActivity")
+    request.requiresExternalPower = false
+    request.requiresNetworkConnectivity = false
+    request.earliestBeginDate = earliestBeginDate
+    try backgroundTaskClient.submit(taskRequest: request)
+  }
 }