diff --git a/src/main/java/com/example/tampopotest/controller/ActivityController.java b/src/main/java/com/example/tampopotest/controller/ActivityController.java
new file mode 100644
index 0000000..cb46b76
--- /dev/null
+++ b/src/main/java/com/example/tampopotest/controller/ActivityController.java
@@ -0,0 +1,246 @@
+package com.example.tampopotest.controller;
+
+import com.example.tampopotest.entity.Activity;
+import com.example.tampopotest.entity.User;
+import com.example.tampopotest.repository.ActivityRepository;
+import com.example.tampopotest.repository.UserRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.web.bind.annotation.*;
+
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import java.util.*;
+import java.util.stream.Collectors;
+
+@RestController
+@RequestMapping("/users/{user-id}/activities")
+public class ActivityController {
+    
+    @Autowired
+    private ActivityRepository activityRepository;
+    
+    @Autowired
+    private UserRepository userRepository;
+    
+    // GET /users/{user-id}/activities - アクティビティ一覧を返す
+    @GetMapping
+    public ResponseEntity<?> getActivities(@PathVariable("user-id") String userId) {
+        try {
+            Optional<User> userOpt = userRepository.findByUserId(userId);
+            if (userOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            List<Activity> activities = activityRepository.findByUserId(userId);
+            List<Map<String, Object>> response = activities.stream()
+                    .map(activity -> {
+                        Map<String, Object> activityMap = new HashMap<>();
+                        activityMap.put("activity-id", activity.getActivityId());
+                        activityMap.put("text", activity.getText());
+                        activityMap.put("updated-time", activity.getUpdatedTime() != null ? 
+                                activity.getUpdatedTime().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME) : null);
+                        return activityMap;
+                    })
+                    .collect(Collectors.toList());
+            
+            return ResponseEntity.ok(response);
+        } catch (Exception e) {
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("予期せぬエラー");
+        }
+    }
+    
+    // POST /users/{user-id}/activities - アクティビティの作成
+    @PostMapping(consumes = "application/x-www-form-urlencoded")
+    public ResponseEntity<?> createActivity(@PathVariable("user-id") String userId,
+                                            @RequestParam("token") String token,
+                                            @RequestParam("activity-id") String activityId) {
+        try {
+            Optional<User> userOpt = userRepository.findByUserId(userId);
+            if (userOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            User user = userOpt.get();
+            if (user.getToken() == null) {
+                return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body("未認証");
+            }
+            
+            if (!user.getToken().equals(token)) {
+                return ResponseEntity.status(HttpStatus.FORBIDDEN).body("トークンの不一致");
+            }
+            
+            Activity activity = new Activity(activityId, userId);
+            activityRepository.save(activity);
+            
+            Map<String, Object> response = new HashMap<>();
+            response.put("activity-id", activity.getActivityId());
+            response.put("text", activity.getText());
+            response.put("updated-time", activity.getUpdatedTime() != null ? 
+                    activity.getUpdatedTime().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME) : null);
+            
+            return ResponseEntity.ok(response);
+        } catch (Exception e) {
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("予期せぬエラー");
+        }
+    }
+    
+    // GET /users/{user-id}/activities/{activity-id} - 単一アクティビティを返す
+    @GetMapping("/{activity-id}")
+    public ResponseEntity<?> getActivity(@PathVariable("user-id") String userId,
+                                         @PathVariable("activity-id") String activityId) {
+        try {
+            Optional<Activity> activityOpt = activityRepository.findByUserIdAndActivityId(userId, activityId);
+            if (activityOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            Activity activity = activityOpt.get();
+            Map<String, Object> response = new HashMap<>();
+            response.put("activity-id", activity.getActivityId());
+            response.put("text", activity.getText());
+            response.put("updated-time", activity.getUpdatedTime() != null ? 
+                    activity.getUpdatedTime().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME) : null);
+            
+            return ResponseEntity.ok(response);
+        } catch (Exception e) {
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("予期せぬエラー");
+        }
+    }
+    
+    // DELETE /users/{user-id}/activities/{activity-id} - アクティビティの削除
+    @DeleteMapping("/{activity-id}")
+    @Transactional
+    public ResponseEntity<?> deleteActivity(@PathVariable("user-id") String userId,
+                                            @PathVariable("activity-id") String activityId,
+                                            @RequestParam("token") String token) {
+        try {
+            Optional<User> userOpt = userRepository.findByUserId(userId);
+            if (userOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            User user = userOpt.get();
+            if (user.getToken() == null) {
+                return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body("未認証");
+            }
+            
+            if (!user.getToken().equals(token)) {
+                return ResponseEntity.status(HttpStatus.FORBIDDEN).body("トークンの不一致");
+            }
+            
+            Optional<Activity> activityOpt = activityRepository.findByUserIdAndActivityId(userId, activityId);
+            if (activityOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            activityRepository.deleteByUserIdAndActivityId(userId, activityId);
+            return ResponseEntity.ok().build();
+        } catch (Exception e) {
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("予期せぬエラー");
+        }
+    }
+    
+    // GET /users/{user-id}/activities/{activity-id}/text - アクティビティのテキスト取得
+    @GetMapping("/{activity-id}/text")
+    public ResponseEntity<?> getActivityText(@PathVariable("user-id") String userId,
+                                             @PathVariable("activity-id") String activityId) {
+        try {
+            Optional<Activity> activityOpt = activityRepository.findByUserIdAndActivityId(userId, activityId);
+            if (activityOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            return ResponseEntity.ok(activityOpt.get().getText());
+        } catch (Exception e) {
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("予期せぬエラー");
+        }
+    }
+    
+    // PUT /users/{user-id}/activities/{activity-id}/text - アクティビティのテキスト更新
+    @PutMapping(value = "/{activity-id}/text", consumes = "application/x-www-form-urlencoded")
+    public ResponseEntity<?> updateActivityText(@PathVariable("user-id") String userId,
+                                                @PathVariable("activity-id") String activityId,
+                                                @RequestParam("token") String token,
+                                                @RequestParam("new-text") String newText) {
+        try {
+            Optional<User> userOpt = userRepository.findByUserId(userId);
+            if (userOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            User user = userOpt.get();
+            if (user.getToken() == null) {
+                return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body("未認証");
+            }
+            
+            if (!user.getToken().equals(token)) {
+                return ResponseEntity.status(HttpStatus.FORBIDDEN).body("トークンの不一致");
+            }
+            
+            Optional<Activity> activityOpt = activityRepository.findByUserIdAndActivityId(userId, activityId);
+            if (activityOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            Activity activity = activityOpt.get();
+            activity.setText(newText);
+            activity.setUpdatedTime(LocalDateTime.now());
+            activityRepository.save(activity);
+            
+            return ResponseEntity.ok(activity.getText());
+        } catch (Exception e) {
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("予期せぬエラー");
+        }
+    }
+    
+    // GET /users/{user-id}/activities/{activity-id}/updated-time - アクティビティの更新時刻取得
+    @GetMapping("/{activity-id}/updated-time")
+    public ResponseEntity<?> getActivityUpdatedTime(@PathVariable("user-id") String userId,
+                                                    @PathVariable("activity-id") String activityId) {
+        try {
+            Optional<Activity> activityOpt = activityRepository.findByUserIdAndActivityId(userId, activityId);
+            if (activityOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            Activity activity = activityOpt.get();
+            String updatedTime = activity.getUpdatedTime() != null ? 
+                    activity.getUpdatedTime().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME) : null;
+            
+            return ResponseEntity.ok(updatedTime);
+        } catch (Exception e) {
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("予期せぬエラー");
+        }
+    }
+    
+    // GET /users/{user-id}/activities/last-updated-time - 最終更新時刻取得
+    @GetMapping("/last-updated-time")
+    public ResponseEntity<?> getLastUpdatedTime(@PathVariable("user-id") String userId) {
+        try {
+            Optional<User> userOpt = userRepository.findByUserId(userId);
+            if (userOpt.isEmpty()) {
+                return ResponseEntity.status(HttpStatus.NOT_FOUND).body("データが存在しません");
+            }
+            
+            List<Activity> activities = activityRepository.findByUserId(userId);
+            if (activities.isEmpty()) {
+                return ResponseEntity.ok(null);
+            }
+            
+            Optional<LocalDateTime> lastUpdated = activities.stream()
+                    .map(Activity::getUpdatedTime)
+                    .filter(Objects::nonNull)
+                    .max(LocalDateTime::compareTo);
+            
+            String result = lastUpdated.map(time -> time.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME))
+                    .orElse(null);
+            
+            return ResponseEntity.ok(result);
+        } catch (Exception e) {
+            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("予期せぬエラー");
+        }
+    }
+}