diff --git a/.github/workflows/test-server-ci.yml b/.github/workflows/test-server-ci.yml
index 36cb6d37..7bb707d2 100644
--- a/.github/workflows/test-server-ci.yml
+++ b/.github/workflows/test-server-ci.yml
@@ -90,6 +90,7 @@ jobs:
           AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
           AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
           AWS_S3_BUCKET_NAME: ${{ secrets.AWS_S3_BUCKET_NAME }}
+          AWS_S3_PREFIX: test/
           SENTRY_DSN: ${{ secrets.SENTRY_DSN }}
           JWT_SECRET_KEY: ${{ secrets.JWT_SECRET_KEY }}
           JWT_ACCESS_TOKEN_VALIDITY: ${{ secrets.JWT_ACCESS_TOKEN_VALIDITY }}
diff --git a/src/main/java/org/tuna/zoopzoop/backend/domain/space/space/service/SpaceService.java b/src/main/java/org/tuna/zoopzoop/backend/domain/space/space/service/SpaceService.java
index 3e164420..cc9c464b 100644
--- a/src/main/java/org/tuna/zoopzoop/backend/domain/space/space/service/SpaceService.java
+++ b/src/main/java/org/tuna/zoopzoop/backend/domain/space/space/service/SpaceService.java
@@ -3,10 +3,13 @@
 import jakarta.persistence.NoResultException;
 import jakarta.validation.constraints.NotBlank;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.hibernate.validator.constraints.Length;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.dao.DataIntegrityViolationException;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.StringUtils;
 import org.springframework.web.multipart.MultipartFile;
 import org.tuna.zoopzoop.backend.domain.datasource.repository.DataSourceRepository;
 import org.tuna.zoopzoop.backend.domain.datasource.repository.TagRepository;
@@ -18,6 +21,7 @@
 import org.tuna.zoopzoop.backend.global.aws.S3Service;
 import org.tuna.zoopzoop.backend.global.clients.liveblocks.LiveblocksClient;
 
+@Slf4j
 @Service
 @RequiredArgsConstructor
 public class SpaceService {
@@ -28,6 +32,9 @@ public class SpaceService {
     private final TagRepository tagRepository;
     private final DataSourceRepository dataSourceRepository;
 
+    @Value("${spring.cloud.aws.s3.prefix}")
+    private String s3Prefix;
+
     // ======================== 스페이스 조회 ======================== //
 
     /**
@@ -174,9 +181,10 @@ public void updateSpaceThumbnail(Integer spaceId, Member requester, MultipartFil
         }
 
         try {
-            //String fileName = "space/" + spaceId + "/thumbnail/" + System.currentTimeMillis() + "_" +
+            //String fileName = "space-thumbnail/prefix/space_id.jpg";
             // S3 저장 시 파일 이름 고정 (덮어쓰기)
-            String fileName = "space-thumbnail/space_" + spaceId ;
+            String extension = StringUtils.getFilenameExtension(image.getOriginalFilename());
+            String fileName = "space-thumbnail/" + s3Prefix + "/space_" + spaceId + "." + extension;
             String baseImageUrl = s3Service.upload(image, fileName);
 
             // DB 용으로 현재 시간을 쿼리 파라미터에 추가 (캐시 무효화)
@@ -186,6 +194,7 @@ public void updateSpaceThumbnail(Integer spaceId, Member requester, MultipartFil
             space.setThumbnailUrl(finalImageUrl);
             spaceRepository.save(space);
         } catch (Exception e) {
+            log.error("Space thumbnail upload failed: ", e);
             throw new RuntimeException("스페이스 썸네일 이미지 업로드에 실패했습니다.");
         }
     }
diff --git a/src/main/resources/application.yml b/src/main/resources/application.yml
index 4b012f4b..e6687ffd 100644
--- a/src/main/resources/application.yml
+++ b/src/main/resources/application.yml
@@ -108,9 +108,11 @@ spring:
         static: ap-northeast-2
       s3:
         bucket: ${AWS_S3_BUCKET_NAME}
+        prefix: ${AWS_S3_PREFIX}
       stack:
         auto: false
 
+
 #Spring doc 설정
 springdoc:
   default-produces-media-type: application/json;charset=UTF-8