diff --git a/BACK/spring-app/src/main/java/com/starchive/springapp/category/domain/Category.java b/BACK/spring-app/src/main/java/com/starchive/springapp/category/domain/Category.java
index 4a74d6d..c85560d 100644
--- a/BACK/spring-app/src/main/java/com/starchive/springapp/category/domain/Category.java
+++ b/BACK/spring-app/src/main/java/com/starchive/springapp/category/domain/Category.java
@@ -6,6 +6,7 @@
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
@@ -23,7 +24,7 @@
 @Table(name = "Categories")
 public class Category {
     @Id
-    @GeneratedValue
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     @Column(name = "categoryId")
     private Long id;
 
diff --git a/BACK/spring-app/src/main/java/com/starchive/springapp/hashtag/domain/HashTag.java b/BACK/spring-app/src/main/java/com/starchive/springapp/hashtag/domain/HashTag.java
index 2be4d8f..b23923f 100644
--- a/BACK/spring-app/src/main/java/com/starchive/springapp/hashtag/domain/HashTag.java
+++ b/BACK/spring-app/src/main/java/com/starchive/springapp/hashtag/domain/HashTag.java
@@ -3,6 +3,7 @@
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.Table;
 import lombok.AccessLevel;
@@ -15,7 +16,7 @@
 @Getter
 public class HashTag {
     @Id
-    @GeneratedValue
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     @Column(name = "hashTagId")
     private Long id;
 
diff --git a/BACK/spring-app/src/main/java/com/starchive/springapp/post/service/PostService.java b/BACK/spring-app/src/main/java/com/starchive/springapp/post/service/PostService.java
index 75eac41..b914166 100644
--- a/BACK/spring-app/src/main/java/com/starchive/springapp/post/service/PostService.java
+++ b/BACK/spring-app/src/main/java/com/starchive/springapp/post/service/PostService.java
@@ -72,7 +72,7 @@ public PostListResponse findPosts(Long categoryId, Long hashTagId, int pageNum,
                 postIds.add(postHashTag.getPost().getId());
             }
             if (postIds.isEmpty()) {
-                postIds = null;
+                return PostListResponse.from(Page.empty());
             }
         }