diff --git a/data/src/main/java/one/nem/kidshift/data/impl/KSActionsImpl.java b/data/src/main/java/one/nem/kidshift/data/impl/KSActionsImpl.java
index 786bb38..5b654ca 100644
--- a/data/src/main/java/one/nem/kidshift/data/impl/KSActionsImpl.java
+++ b/data/src/main/java/one/nem/kidshift/data/impl/KSActionsImpl.java
@@ -24,10 +24,10 @@ import retrofit2.Response;
 
 public class KSActionsImpl implements KSActions {
 
-    private UserSettings userSettings;
-    private KidShiftApiService kidShiftApiService;
-    private KSLogger logger;
-    private CacheWrapper cacheWrapper;
+    private final UserSettings userSettings;
+    private final KidShiftApiService kidShiftApiService;
+    private final KSLogger logger;
+    private final CacheWrapper cacheWrapper;
 
     @Inject
     public KSActionsImpl(UserSettings userSettings, KidShiftApiService kidShiftApiService, KSLogger logger, CacheWrapper cacheWrapper) {
diff --git a/data/src/main/java/one/nem/kidshift/data/impl/ParentDataImpl.java b/data/src/main/java/one/nem/kidshift/data/impl/ParentDataImpl.java
index a8f70d6..4fcfe57 100644
--- a/data/src/main/java/one/nem/kidshift/data/impl/ParentDataImpl.java
+++ b/data/src/main/java/one/nem/kidshift/data/impl/ParentDataImpl.java
@@ -14,17 +14,14 @@ import one.nem.kidshift.utils.KSLogger;
 
 public class ParentDataImpl implements ParentData {
 
-    private KidShiftApiService kidshiftApiService;
+    private final UserSettings userSettings;
 
-    private UserSettings userSettings;
+    private final KSLogger logger;
 
-    private KSLogger logger;
-
-    private KSActions ksActions;
+    private final KSActions ksActions;
 
     @Inject
     public ParentDataImpl(KidShiftApiService kidshiftApiService, UserSettings userSettings, KSLogger logger, KSActions ksActions) {
-        this.kidshiftApiService = kidshiftApiService;
         this.userSettings = userSettings;
         this.logger = logger;
         this.ksActions = ksActions;
diff --git a/data/src/main/java/one/nem/kidshift/data/impl/TaskDataImpl.java b/data/src/main/java/one/nem/kidshift/data/impl/TaskDataImpl.java
index 4e13e85..2ce4397 100644
--- a/data/src/main/java/one/nem/kidshift/data/impl/TaskDataImpl.java
+++ b/data/src/main/java/one/nem/kidshift/data/impl/TaskDataImpl.java
@@ -1,16 +1,14 @@
 package one.nem.kidshift.data.impl;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
-import java.util.stream.Collectors;
+import java.util.concurrent.atomic.AtomicReference;
 
 import javax.inject.Inject;
-import javax.security.auth.callback.Callback;
 
 import one.nem.kidshift.data.KSActions;
 import one.nem.kidshift.data.TaskData;
-import one.nem.kidshift.data.retrofit.model.converter.TaskModelConverter;
-import one.nem.kidshift.data.retrofit.model.task.TaskListResponse;
 import one.nem.kidshift.data.room.utils.CacheWrapper;
 import one.nem.kidshift.model.callback.TaskItemModelCallback;
 import one.nem.kidshift.model.tasks.TaskItemModel;
@@ -18,9 +16,9 @@ import one.nem.kidshift.utils.KSLogger;
 
 public class TaskDataImpl implements TaskData {
 
-    private KSActions ksActions;
-    private CacheWrapper cacheWrapper;
-    private KSLogger logger;
+    private final KSActions ksActions;
+    private final CacheWrapper cacheWrapper;
+    private final KSLogger logger;
 
     @Inject
     public TaskDataImpl(KSActions ksActions, CacheWrapper cacheWrapper, KSLogger logger) {
@@ -31,30 +29,74 @@ public class TaskDataImpl implements TaskData {
 
     @Override
     public CompletableFuture<List<TaskItemModel>> getTasks(TaskItemModelCallback callback) {
-        return CompletableFuture.supplyAsync(() -> {
-            logger.debug("タスク取得開始");
-            Thread thread = new Thread(() -> {
-                // TODO-rca: ちゃんと比較して呼ぶ
-                ksActions.syncTasks().thenAccept(callback::onUpdated);
-            });
-            thread.start();
-            return cacheWrapper.getTaskList().thenApply(taskList -> {
-                if (taskList == null || taskList.isEmpty()) {
-                    try {
-                        logger.debug("キャッシュ無: タスク取得スレッド待機");
-                        thread.join();
-                        return cacheWrapper.getTaskList().join();
-                    } catch (InterruptedException e) {
-                        throw new RuntimeException(e);
-                    }
-                } else {
-                    logger.debug("キャッシュ有 (タスク数: " + taskList.size() + ")");
-                    return taskList;
-                }
-            }).join();
+        logger.debug("タスク取得開始");
+
+        CompletableFuture<List<TaskItemModel>> cachedTasksFuture = cacheWrapper.getTaskList();
+
+        return cachedTasksFuture.thenCompose(cachedTasks -> {
+            if (cachedTasks == null || cachedTasks.isEmpty()) {
+                logger.debug("キャッシュ無: サーバーからタスクを取得");
+                return fetchTasksFromServer(callback);
+            } else {
+                logger.debug("キャッシュ有 (タスク数: " + cachedTasks.size() + ")");
+                return checkForUpdates(cachedTasks, callback);
+            }
         });
     }
 
+    private CompletableFuture<List<TaskItemModel>> fetchTasksFromServer(TaskItemModelCallback callback) {
+        return ksActions.syncTasks().thenApply(serverTasks -> {
+            if (serverTasks == null || serverTasks.isEmpty()) {
+                callback.onUnchanged();
+            } else {
+                callback.onUpdated(serverTasks);
+            }
+            return serverTasks;
+        }).exceptionally(e -> {
+            logger.error("タスク取得失敗: " + e.getMessage());
+            callback.onFailed(e.getMessage());
+            return Collections.emptyList();
+        });
+    }
+
+    private CompletableFuture<List<TaskItemModel>> checkForUpdates(List<TaskItemModel> cachedTasks, TaskItemModelCallback callback) {
+        return ksActions.syncTasks().thenApply(serverTasks -> {
+            if (serverTasks == null || serverTasks.isEmpty()) {
+                callback.onUnchanged();
+                return cachedTasks;
+            } else {
+                boolean isChanged = isTaskListChanged(cachedTasks, serverTasks);
+                if (isChanged) {
+                    logger.debug("タスク取得完了: キャッシュと比較して変更あり");
+                    callback.onUpdated(serverTasks);
+                    return serverTasks;
+                } else {
+                    logger.debug("タスク取得完了: キャッシュと比較して変更なし");
+                    callback.onUnchanged();
+                    return cachedTasks;
+                }
+            }
+        }).exceptionally(e -> {
+            logger.error("タスク取得失敗: " + e.getMessage());
+            callback.onFailed(e.getMessage());
+            return cachedTasks;
+        });
+    }
+
+    private boolean isTaskListChanged(List<TaskItemModel> cachedTasks, List<TaskItemModel> serverTasks) {
+        if (cachedTasks.size() != serverTasks.size()) {
+            return true;
+        }
+
+        for (TaskItemModel serverTask : serverTasks) {
+            boolean exists = cachedTasks.stream().anyMatch(cachedTask -> serverTask.getId().equals(cachedTask.getId()));
+            if (!exists) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     @Override
     public CompletableFuture<List<TaskItemModel>> getTasks(String childId, TaskItemModelCallback callback) {
         return null;