diff --git a/src/main/java/com/bamboo/log/diary/dto/response/CheckDiaryResponse.java b/src/main/java/com/bamboo/log/diary/dto/response/CheckDiaryResponse.java
index ad365f7..152e4db 100644
--- a/src/main/java/com/bamboo/log/diary/dto/response/CheckDiaryResponse.java
+++ b/src/main/java/com/bamboo/log/diary/dto/response/CheckDiaryResponse.java
@@ -1,13 +1,22 @@
 package com.bamboo.log.diary.dto.response;
 
+import com.bamboo.log.diary.domain.Diary;
 import jakarta.validation.constraints.NotEmpty;
 import lombok.Builder;
-
 import java.time.LocalDateTime;
+import java.util.Base64;
 
 @Builder
-public record CheckDiaryResponse(@NotEmpty(message = "Date shouldn't be empty") LocalDateTime date,
-                                 @NotEmpty(message = "Diary Description shouldn't be empty") String diaryDescription,
-                                 @NotEmpty(message = "Summary Image shouldn't be empty") byte[] summaryImage
+public record CheckDiaryResponse(
+        @NotEmpty(message = "Date shouldn't be empty") LocalDateTime date,
+        @NotEmpty(message = "Diary Description shouldn't be empty") String diaryDescription,
+        String summaryImage  // 👈 Base64 문자열로 변경 (byte[] 대신 String)
 ) {
-}
\ No newline at end of file
+    public static CheckDiaryResponse from(Diary diary, byte[] imageData) {
+        return new CheckDiaryResponse(
+                diary.getCreatedAt(),
+                diary.getContext(),
+                imageData != null ? Base64.getEncoder().encodeToString(imageData) : null
+        );
+    }
+}
diff --git a/src/main/java/com/bamboo/log/diary/dto/response/GetDiariesOfMonthResponse.java b/src/main/java/com/bamboo/log/diary/dto/response/GetDiariesOfMonthResponse.java
index 96285a3..6440971 100644
--- a/src/main/java/com/bamboo/log/diary/dto/response/GetDiariesOfMonthResponse.java
+++ b/src/main/java/com/bamboo/log/diary/dto/response/GetDiariesOfMonthResponse.java
@@ -1,7 +1,6 @@
 package com.bamboo.log.diary.dto.response;
 
 import lombok.Builder;
-
 import java.time.LocalDateTime;
 import java.util.List;
 
@@ -11,12 +10,10 @@ public record GetDiariesOfMonthResponse(
         String date,
         List<DiaryOfMonth> diaries
 ) {
-
     @Builder
     public record DiaryOfMonth(
             LocalDateTime createdAt,
             String context,
-            byte[] summaryImage
+            String summaryImage
     ) {}
-
 }
diff --git a/src/main/java/com/bamboo/log/diary/service/diary/DiaryServiceImpl.java b/src/main/java/com/bamboo/log/diary/service/diary/DiaryServiceImpl.java
index 315ad07..9d62714 100644
--- a/src/main/java/com/bamboo/log/diary/service/diary/DiaryServiceImpl.java
+++ b/src/main/java/com/bamboo/log/diary/service/diary/DiaryServiceImpl.java
@@ -27,6 +27,7 @@
 import java.time.LocalDateTime;
 import java.time.YearMonth;
 import java.time.format.DateTimeFormatter;
+import java.util.Base64;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -70,15 +71,17 @@ public ResponseEntity getDiariesByMonth(String date) {
                     parseYearMonth.getStartOfMonth(), parseYearMonth.getEndOfMonth());
 
             List<Long> diaryIds = diaries.stream().map(Diary::getId).toList();
-            Map<Long, byte[]> summaryImageMap = todaySummaryRepository.findByDiaryIdIn(diaryIds)
+            Map<Long, String> summaryImageMap = todaySummaryRepository.findByDiaryIdIn(diaryIds)
                     .stream()
-                    .collect(Collectors.toMap(TodaySummary::getDiaryId, TodaySummary::getImageData));
+                    .collect(Collectors.toMap(
+                            TodaySummary::getDiaryId,
+                            summary -> Base64.getEncoder().encodeToString(summary.getImageData()))); // ✅ Base64 변환
 
             List<DiaryOfMonth> diaryOfMonthList = diaries.stream()
                     .map(diary -> new DiaryOfMonth(
                             diary.getCreatedAt(),
                             diary.getContext(),
-                            summaryImageMap.getOrDefault(diary.getId(), null)
+                            summaryImageMap.getOrDefault(diary.getId(), null) // Base64 문자열 전달
                     ))
                     .toList();
 
@@ -110,12 +113,7 @@ public ResponseEntity getDiaryByDate(LocalDateTime date) {
             Optional<TodaySummary> summaryImage = todaySummaryRepository.findByDiaryId(diaryByDate.getId());
 
             return ResponseHandler.create200Response(new ResponseForm(),
-                    CheckDiaryResponse.builder()
-                            .date(diaryByDate.getCreatedAt())
-                            .diaryDescription(diaryByDate.getContext())
-                            .summaryImage(summaryImage.map(TodaySummary::getImageData).orElse(null))
-                            .build());
-
+                    CheckDiaryResponse.from(diaryByDate, summaryImage.map(TodaySummary::getImageData).orElse(null)));
         } catch (RuntimeException e) {
             return ResponseHandler.create404Error(new ResponseForm(), new IllegalArgumentException("해당 날짜에 작성된 일기가 없습니다."));
         } catch (Exception e) {
@@ -123,6 +121,7 @@ public ResponseEntity getDiaryByDate(LocalDateTime date) {
         }
     }
 
+
     private Diary saveDiary(CreateDiaryRequest createDiaryRequest, LocalDateTime localDateTime) {
         UserEntity user = userContextUtil.getUserEntity();