diff --git a/src/main/java/umc_haekathon_4/demo/service/MissionService.java b/src/main/java/umc_haekathon_4/demo/service/MissionService.java
index 4399798..7d2cdea 100644
--- a/src/main/java/umc_haekathon_4/demo/service/MissionService.java
+++ b/src/main/java/umc_haekathon_4/demo/service/MissionService.java
@@ -1,16 +1,40 @@
 package umc_haekathon_4.demo.service;
 
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 import umc_haekathon_4.demo.domain.Mission;
+import umc_haekathon_4.demo.domain.TreasureBox;
 import umc_haekathon_4.demo.repository.MissionRepository;
 
+import java.util.Optional;
+
+@Service
 public class MissionService {
 
-    private MissionRepository missionRepository;
+    private final MissionRepository missionRepository;
 
+    @Autowired
+    public MissionService(MissionRepository missionRepository) {
+        this.missionRepository = missionRepository;
+    }
+/*
     @Transactional(readOnly = true)
     public Mission findMissionById(Long missionId) {
         return missionRepository.findById(missionId)
-                .orElseThrow(()->new RuntimeException("Mission not found"));
+                .orElseThrow(() -> new RuntimeException("Mission not found with id: " + missionId));
+    }*/
+
+    @Transactional(readOnly = true)
+    public Mission findMissionByIdOrDefault(Long missionId) {
+        return missionRepository.findById(missionId)
+                .orElse(getDefaultMission());
+    }
+
+    private Mission getDefaultMission() {
+        Mission defaultMission = new Mission();
+        defaultMission.setBody("This is a default mission.");
+        return defaultMission;
     }
+
 }
diff --git a/src/main/java/umc_haekathon_4/demo/web/controller/MissionController.java b/src/main/java/umc_haekathon_4/demo/web/controller/MissionController.java
index ad6ab70..c3ae91a 100644
--- a/src/main/java/umc_haekathon_4/demo/web/controller/MissionController.java
+++ b/src/main/java/umc_haekathon_4/demo/web/controller/MissionController.java
@@ -5,9 +5,12 @@
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 import umc_haekathon_4.demo.apiPayload.ApiResponse;
+import umc_haekathon_4.demo.apiPayload.code.ErrorReasonDTO;
 import umc_haekathon_4.demo.domain.Mission;
 import umc_haekathon_4.demo.service.MissionService;
 
+import java.util.Optional;
+
 @RestController
 @RequiredArgsConstructor
 @RequestMapping("/")
@@ -15,11 +18,13 @@ public class MissionController {
 
     private final MissionService missionService;
 
+
     //미션 주기
     @GetMapping("/mission")
     public ApiResponse<Mission> getMission(Long missionId){
-        Mission mission = missionService.findMissionById(missionId);
+        Mission mission = missionService.findMissionByIdOrDefault(missionId);
         return ApiResponse.onSuccess(mission);
     }
 
+
 }