diff --git a/android/app/src/main/AndroidManifest.xml b/android/app/src/main/AndroidManifest.xml
index 6f6b4774..618c5d1c 100644
--- a/android/app/src/main/AndroidManifest.xml
+++ b/android/app/src/main/AndroidManifest.xml
@@ -44,6 +44,17 @@
         <meta-data
             android:name="flutterEmbedding"
             android:value="2" />
+        <service
+            android:name=".FocusAccessibilityService"
+            android:permission="android.permission.BIND_ACCESSIBILITY_SERVICE"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.accessibilityservice.AccessibilityService" />
+            </intent-filter>
+            <meta-data
+                android:name="android.accessibilityservice"
+                android:resource="@xml/accessibility_service_config" />
+        </service>
     </application>
     <!-- Required to query activities that can process text, see:
          https://developer.android.com/training/package-visibility and
diff --git a/android/app/src/main/kotlin/com/company/bookstar/FocusAccessibilityService.kt b/android/app/src/main/kotlin/com/company/bookstar/FocusAccessibilityService.kt
new file mode 100644
index 00000000..8680dce4
--- /dev/null
+++ b/android/app/src/main/kotlin/com/company/bookstar/FocusAccessibilityService.kt
@@ -0,0 +1,71 @@
+package com.company.bookstar
+
+import android.accessibilityservice.AccessibilityService
+import android.view.accessibility.AccessibilityEvent
+import android.content.Context
+import android.content.Intent
+import android.content.SharedPreferences
+import android.util.Log
+
+class FocusAccessibilityService : AccessibilityService() {
+
+    companion object {
+        private const val TAG = "FocusAccessibility"
+        private const val PREFS_NAME = "FocusModePrefs"
+        private const val KEY_IS_ACTIVE = "is_active"
+        // Whitelisted packages: Our app + Keyboards
+        private val WHITELISTED_PACKAGES = setOf(
+            "com.company.bookstar",
+            "com.google.android.inputmethod.latin", // Gboard
+            "com.samsung.android.honeyboard" // Samsung Keyboard
+        )
+    }
+
+    override fun onAccessibilityEvent(event: AccessibilityEvent?) {
+        // We only care about window state changes (app switching)
+        if (event == null || event.eventType != AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED) {
+            return
+        }
+
+        val packageName = event.packageName?.toString() ?: return
+        
+        // Check if blocking is enabled from SharedPrefs
+        val prefs: SharedPreferences = getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
+        val isBlocking = prefs.getBoolean(KEY_IS_ACTIVE, false)
+
+        if (isBlocking) {
+            if (!isPackageAllowed(packageName)) {
+                Log.d(TAG, "Blocking package: $packageName")
+                
+                // Action: Bring our app to front to make it clear why
+                val intent = packageManager.getLaunchIntentForPackage("com.company.bookstar")
+                if (intent != null) {
+                    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TOP or Intent.FLAG_ACTIVITY_SINGLE_TOP)
+                    startActivity(intent)
+                }
+            }
+        }
+    }
+
+    private fun isPackageAllowed(packageName: String): Boolean {
+        // 1. Check exact whitelist
+        if (WHITELISTED_PACKAGES.contains(packageName)) return true
+        
+        // 2. Allow input methods (Keyboards) - Critical for user interaction
+        if (packageName.contains("inputmethod") || packageName.contains("keyboard")) return true
+
+        // 3. Allow System UI (Notifications, Quick Settings)
+        if (packageName == "com.android.systemui") return true
+        
+        return false
+    }
+
+    override fun onInterrupt() {
+        Log.d(TAG, "FocusAccessibilityService interrupted")
+    }
+    
+    override fun onServiceConnected() {
+        super.onServiceConnected()
+        Log.d(TAG, "FocusAccessibilityService connected")
+    }
+}
diff --git a/android/app/src/main/kotlin/com/company/bookstar/MainActivity.kt b/android/app/src/main/kotlin/com/company/bookstar/MainActivity.kt
new file mode 100644
index 00000000..45f74c7d
--- /dev/null
+++ b/android/app/src/main/kotlin/com/company/bookstar/MainActivity.kt
@@ -0,0 +1,73 @@
+package com.company.bookstar
+
+import android.content.ComponentName
+import android.content.Context
+import android.content.Intent
+import android.provider.Settings
+import android.text.TextUtils
+import androidx.annotation.NonNull
+import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugin.common.MethodChannel
+
+class MainActivity : FlutterActivity() {
+    // Channel name as requested
+    private val CHANNEL = "com.example.blocker/control"
+
+    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
+        super.configureFlutterEngine(flutterEngine)
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler { call, result ->
+            when (call.method) {
+                "startBlock" -> {
+                    val prefs = getSharedPreferences("FocusModePrefs", Context.MODE_PRIVATE)
+                    prefs.edit().putBoolean("is_active", true).apply()
+                    result.success(true)
+                }
+                "stopBlock" -> {
+                    val prefs = getSharedPreferences("FocusModePrefs", Context.MODE_PRIVATE)
+                    prefs.edit().putBoolean("is_active", false).apply()
+                    result.success(true)
+                }
+                "requestPermission" -> {
+                    if (!isAccessibilityServiceEnabled()) {
+                        val intent = Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS)
+                        // Add flags to ensure proper navigation behavior
+                        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+                        startActivity(intent)
+                        result.success(true) // Indicates we launched the settings
+                    } else {
+                        result.success(false) // Permission already granted
+                    }
+                }
+                "checkPermission" -> {
+                    result.success(isAccessibilityServiceEnabled())
+                }
+                else -> {
+                    result.notImplemented()
+                }
+            }
+        }
+    }
+
+    // Helper method to check if the Accessibility Service is enabled
+    private fun isAccessibilityServiceEnabled(): Boolean {
+        val expectedComponentName = ComponentName(this, FocusAccessibilityService::class.java)
+        
+        val enabledServicesSetting = Settings.Secure.getString(
+            contentResolver,
+            Settings.Secure.ENABLED_ACCESSIBILITY_SERVICES
+        ) ?: return false
+
+        val colonSplitter = TextUtils.SimpleStringSplitter(':')
+        colonSplitter.setString(enabledServicesSetting)
+
+        while (colonSplitter.hasNext()) {
+            val componentNameString = colonSplitter.next()
+            val enabledComponent = ComponentName.unflattenFromString(componentNameString)
+            if (enabledComponent != null && enabledComponent == expectedComponentName) {
+                return true
+            }
+        }
+        return false
+    }
+}
diff --git a/android/app/src/main/kotlin/com/example/book/MainActivity.kt b/android/app/src/main/kotlin/com/example/book/MainActivity.kt
deleted file mode 100644
index 9d309895..00000000
--- a/android/app/src/main/kotlin/com/example/book/MainActivity.kt
+++ /dev/null
@@ -1,5 +0,0 @@
-package com.company.bookstar
-
-import io.flutter.embedding.android.FlutterActivity
-
-class MainActivity : FlutterActivity()
diff --git a/android/app/src/main/res/values/strings.xml b/android/app/src/main/res/values/strings.xml
new file mode 100644
index 00000000..50ceaa86
--- /dev/null
+++ b/android/app/src/main/res/values/strings.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="accessibility_service_description">Used to block distracting apps while the Focus Timer is running.</string>
+</resources>
diff --git a/android/app/src/main/res/xml/accessibility_service_config.xml b/android/app/src/main/res/xml/accessibility_service_config.xml
new file mode 100644
index 00000000..54fb9bc7
--- /dev/null
+++ b/android/app/src/main/res/xml/accessibility_service_config.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<accessibility-service xmlns:android="http://schemas.android.com/apk/res/android"
+    android:accessibilityEventTypes="typeWindowStateChanged"
+    android:accessibilityFeedbackType="feedbackGeneric"
+    android:notificationTimeout="100"
+    android:canRetrieveWindowContent="true"
+    android:description="@string/accessibility_service_description"
+/>
diff --git a/lib/core/native_block_controller.dart b/lib/core/native_block_controller.dart
new file mode 100644
index 00000000..be91033a
--- /dev/null
+++ b/lib/core/native_block_controller.dart
@@ -0,0 +1,51 @@
+import 'package:flutter/services.dart';
+
+class NativeBlockController {
+  static const MethodChannel _channel = MethodChannel('com.example.blocker/control');
+
+  /// 네이티브에 차단 모드 시작을 요청합니다.
+  Future<void> startBlocking() async {
+    try {
+      await _channel.invokeMethod('startBlock');
+      print('Blocking started on native side.');
+    } on PlatformException catch (e) {
+      print("Failed to start blocking: '${e.message}'.");
+    }
+  }
+
+  /// 네이티브에 차단 모드 해제를 요청합니다.
+  Future<void> stopBlocking() async {
+    try {
+      await _channel.invokeMethod('stopBlock');
+      print('Blocking stopped on native side.');
+    } on PlatformException catch (e) {
+      print("Failed to stop blocking: '${e.message}'.");
+    }
+  }
+
+  /// 네이티브에 접근성 권한 요청 (설정 화면으로 이동)을 요청합니다.
+  /// 설정 화면이 열렸으면 true, 이미 권한이 부여되었으면 false를 반환합니다.
+  Future<bool> requestPermission() async {
+    try {
+      final bool? result = await _channel.invokeMethod('requestPermission');
+      print('Permission request sent to native side. Result: $result');
+      return result ?? false; // true if settings were opened, false if already enabled
+    } on PlatformException catch (e) {
+      print("Failed to request permission: '${e.message}'.");
+      return false;
+    }
+  }
+
+  /// 네이티브에 접근성 권한 상태를 확인을 요청합니다.
+  /// 권한이 부여되었으면 true, 아니면 false를 반환합니다.
+  Future<bool> checkPermission() async {
+    try {
+      final bool? result = await _channel.invokeMethod('checkPermission');
+      print('Permission check result from native side: $result');
+      return result ?? false;
+    } on PlatformException catch (e) {
+      print("Failed to check permission: '${e.message}'.");
+      return false;
+    }
+  }
+}
diff --git a/lib/modules/reading_challenge/view/screens/reading_challenge_quiz_deep_time_screen.dart b/lib/modules/reading_challenge/view/screens/reading_challenge_quiz_deep_time_screen.dart
index a989eb21..8ddd98ea 100644
--- a/lib/modules/reading_challenge/view/screens/reading_challenge_quiz_deep_time_screen.dart
+++ b/lib/modules/reading_challenge/view/screens/reading_challenge_quiz_deep_time_screen.dart
@@ -9,6 +9,7 @@ import 'package:bookstar/gen/colors.gen.dart';
 import 'package:bookstar/modules/reading_challenge/view_model/challenge_quiz_view_model.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:bookstar/core/native_block_controller.dart';
 
 class ReadingChallengeQuizDeepTimeScreen extends ConsumerStatefulWidget {
   const ReadingChallengeQuizDeepTimeScreen({
@@ -45,10 +46,14 @@ class _ReadingChallengeQuizDeepTimeScreenState
   @override
   bool get wantKeepAlive => true;
 
+  final NativeBlockController _blockController = NativeBlockController(); // Instantiate NativeBlockController
+  bool _isPermissionGranted = false; // State for accessibility permission
+
   @override
   void initState() {
     super.initState();
     WidgetsBinding.instance.addObserver(this);
+    _checkPermissionStatus(); // Check permission on init
   }
 
   @override
@@ -57,6 +62,48 @@ class _ReadingChallengeQuizDeepTimeScreenState
     super.dispose();
   }
 
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState state) {
+    if (state == AppLifecycleState.resumed) {
+      _checkPermissionStatus(); // Re-check permission when app resumes
+    }
+  }
+
+  // Method to check accessibility permission status
+  Future<void> _checkPermissionStatus() async {
+    final bool granted = await _blockController.checkPermission();
+    if (mounted) {
+      setState(() {
+        _isPermissionGranted = granted;
+      });
+    }
+  }
+
+  Future<bool> _showPermissionGuideDialog() async {
+    final result = await showDialog<bool>(
+      context: context,
+      builder: (context) {
+        return CustomDialog(
+          title: '집중 모드 권한 설정 안내',
+          content: '다른 앱의 실행을 차단하고 독서에 집중하기 위해\n접근성 권한이 필요합니다.\n\n설정 화면에서 \'BookStar\'를 찾아\n권한을 허용해주세요.',
+          titleStyle: AppTexts.b7.copyWith(color: ColorName.w1),
+          contentStyle: AppTexts.b11.copyWith(color: ColorName.g2),
+          // Using a lock icon or similar as a visual cue
+          icon: Assets.icons.icDeepTimeLockClose.svg(width: 80, height: 80), 
+          onCancel: () {
+            Navigator.of(context).pop(false);
+          },
+          onConfirm: () {
+            Navigator.of(context).pop(true);
+          },
+          confirmButtonText: '설정하러 가기',
+          cancelButtonText: '취소',
+        );
+      },
+    );
+    return result ?? false;
+  }
+
   @override
   Widget build(BuildContext context) {
     super.build(context);
@@ -193,8 +240,29 @@ class _ReadingChallengeQuizDeepTimeScreenState
       child: Padding(
         padding: const EdgeInsets.symmetric(horizontal: 16),
         child: GestureDetector(
-          onTap: () {
-            toggleIsLock();
+          onTap: () async {
+            if (!_isPermissionGranted) {
+              // Show dialog to guide user before requesting permission
+              final bool shouldGoToSettings = await _showPermissionGuideDialog();
+              
+              if (shouldGoToSettings) {
+                final bool settingsOpened = await _blockController.requestPermission();
+                if (settingsOpened) {
+                  // Wait for user to possibly enable it and come back
+                  // Note: We can't know exactly when they come back, but lifecycle listener handles re-check
+                }
+              }
+              // Don't proceed to toggle lock if permission wasn't granted yet
+              return;
+            }
+
+            // If permission is granted, proceed with blocking/unblocking logic
+            if (!widget.isLock) { // If currently unlocked (false), tapping means locking (true)
+              await _blockController.startBlocking();
+            } else { // If currently locked (true), tapping means unlocking (false)
+              await _blockController.stopBlocking();
+            }
+            widget.onLockToggle(); // Call original toggle callback to update widget.isLock
           },
           child: !isLock
               ? Assets.icons.icDeepTimeLockOpen.svg()