diff --git a/Spark-iOS/Spark-iOS/Resource/Constants/UserDefaultsKey.swift b/Spark-iOS/Spark-iOS/Resource/Constants/UserDefaultsKey.swift
index f27971d7..9f37d03f 100644
--- a/Spark-iOS/Spark-iOS/Resource/Constants/UserDefaultsKey.swift
+++ b/Spark-iOS/Spark-iOS/Resource/Constants/UserDefaultsKey.swift
@@ -15,5 +15,7 @@ extension Const {
         static let accessToken = "accessToekn"
         static let fcmToken = "fcmToken"
         static let checkHabitRoomGuide = "checkHabitRoomGuide"
+        static let sceneWillEnterForeground = "sceneWillEnterForeground"
+        static let sceneDidEnterBackground = "sceneDidEnterBackground"
     }
 }
diff --git a/Spark-iOS/Spark-iOS/Source/SceneDelegate.swift b/Spark-iOS/Spark-iOS/Source/SceneDelegate.swift
index b70f0113..5902b751 100644
--- a/Spark-iOS/Spark-iOS/Source/SceneDelegate.swift
+++ b/Spark-iOS/Spark-iOS/Source/SceneDelegate.swift
@@ -41,9 +41,18 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
     func sceneWillResignActive(_ scene: UIScene) {
     }
 
+    // Foreground에 들어올 때
+    // sceneDidEnterBackground라는 키워드로 저장해둔 값을 sceneWillEnterForeground라는 키워드 노티의 userInfo로 전달
     func sceneWillEnterForeground(_ scene: UIScene) {
+        guard let start = UserDefaults.standard.object(forKey: Const.UserDefaultsKey.sceneDidEnterBackground) as? Date else { return }
+        let interval = Int(Date().timeIntervalSince(start))
+        NotificationCenter.default.post(name: NSNotification.Name(Const.UserDefaultsKey.sceneWillEnterForeground), object: nil, userInfo: ["time": interval])
     }
 
+    // Background에 들어갈때
+    // sceneDidEnterBackground라는 키워드의 노티 전달하며
+    // sceneDidEnterBackground라는 키워드로 값 저장
     func sceneDidEnterBackground(_ scene: UIScene) {
+        UserDefaults.standard.setValue(Date(), forKey: Const.UserDefaultsKey.sceneDidEnterBackground)
     }
 }
diff --git a/Spark-iOS/Spark-iOS/Source/ViewControllers/Auth/AuthTimer/AuthTimerVC.swift b/Spark-iOS/Spark-iOS/Source/ViewControllers/Auth/AuthTimer/AuthTimerVC.swift
index 33533e84..f3fd42be 100644
--- a/Spark-iOS/Spark-iOS/Source/ViewControllers/Auth/AuthTimer/AuthTimerVC.swift
+++ b/Spark-iOS/Spark-iOS/Source/ViewControllers/Auth/AuthTimer/AuthTimerVC.swift
@@ -50,6 +50,13 @@ class AuthTimerVC: UIViewController {
         navigationController?.interactivePopGestureRecognizer?.delegate = self
     }
     
+    override func viewWillDisappear(_ animated: Bool) {
+        super.viewWillDisappear(animated)
+        
+        NotificationCenter.default.removeObserver(self, name: NSNotification.Name(Const.UserDefaultsKey.sceneWillEnterForeground), object: nil)
+        NotificationCenter.default.removeObserver(self, name: NSNotification.Name(Const.UserDefaultsKey.sceneDidEnterBackground), object: nil)
+    }
+    
     // MARK: - Methods
     
     private func setUI() {
@@ -93,6 +100,7 @@ class AuthTimerVC: UIViewController {
     
     private func setNotification() {
         NotificationCenter.default.addObserver(self, selector: #selector(resetTimer(_:)), name: .resetStopWatch, object: nil)
+        NotificationCenter.default.addObserver(self, selector: #selector(checkBackgroundTimer), name: NSNotification.Name(Const.UserDefaultsKey.sceneWillEnterForeground), object: nil)
     }
     
     private func setButton(_ button: UIButton, title: String, backgroundColor: UIColor, isEnable: Bool) {
@@ -103,7 +111,7 @@ class AuthTimerVC: UIViewController {
         button.layer.cornerRadius = 2
     }
     
-    func dismissAuthTimerVC() {
+    private func dismissAuthTimerVC() {
         if timeLabel.text != "00:00:00" {
             guard let dialogVC = UIStoryboard(name: Const.Storyboard.Name.dialogue, bundle: nil).instantiateViewController(withIdentifier: Const.ViewController.Identifier.dialogue) as? DialogueVC else { return }
             dialogVC.dialogueType = .exitTimer
@@ -118,6 +126,18 @@ class AuthTimerVC: UIViewController {
         }
     }
     
+    private func timeFormatter(_ intTime: Int) -> String {
+        let hour = intTime / 3600
+        let min = (intTime % 3600) / 60
+        let sec = (intTime % 3600) % 60
+        
+        let hourStr =  hour < 10 ? "0\(hour)" : String(hour)
+        let minStr = min < 10 ? "0\(min)" : String(min)
+        let secStr = sec < 10 ? "0\(sec)" : String(sec)
+        
+        return "\(hourStr):\(minStr):\(secStr)"
+    }
+    
     // MARK: - @objc
     
     @objc
@@ -150,16 +170,14 @@ class AuthTimerVC: UIViewController {
         }
     }
     
-    func timeFormatter(_ intTime: Int) -> String {
-        let hour = intTime / 3600
-        let min = (intTime % 3600) / 60
-        let sec = (intTime % 3600) % 60
-        
-        let hourStr =  hour < 10 ? "0\(hour)" : String(hour)
-        let minStr = min < 10 ? "0\(min)" : String(min)
-        let secStr = sec < 10 ? "0\(sec)" : String(sec)
-        
-        return "\(hourStr):\(minStr):\(secStr)"
+    @objc
+    func checkBackgroundTimer(_ notification: NSNotification) {
+        if let isValid = timer?.isValid {
+            if isTimerOn && isValid {
+                let time = notification.userInfo?["time"] as? Int ?? 0
+                currentTimeCount += time
+            }
+        }
     }
     
     @objc