diff --git a/src/main/java/sopt/org/hmh/domain/challenge/service/ChallengeService.java b/src/main/java/sopt/org/hmh/domain/challenge/service/ChallengeService.java
index be6b2be6..f05832e3 100644
--- a/src/main/java/sopt/org/hmh/domain/challenge/service/ChallengeService.java
+++ b/src/main/java/sopt/org/hmh/domain/challenge/service/ChallengeService.java
@@ -83,9 +83,6 @@ public ChallengeResponse getChallenge(Long userId) {
         Challenge challenge = findCurrentChallengeByUserId(userId);
         Integer todayIndex = calculateTodayIndex(challenge.getCreatedAt(), challenge.getPeriod());
 
-        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
-        String formattedStartDate = challenge.getCreatedAt().format(formatter);
-
         return ChallengeResponse.builder()
                 .period(challenge.getPeriod())
                 .statuses(challenge.getHistoryDailyChallenges()
@@ -93,7 +90,7 @@ public ChallengeResponse getChallenge(Long userId) {
                         .map(DailyChallenge::getStatus)
                         .toList())
                 .todayIndex(todayIndex)
-                .startDate(formattedStartDate)
+                .startDate(challenge.getCreatedAt().toLocalDate().toString())
                 .goalTime(challenge.getGoalTime())
                 .apps(challenge.getApps().stream()
                         .map(app -> new AppGoalTimeResponse(app.getAppCode(), app.getGoalTime())).toList())