diff --git a/src/main/java/com/mallang/post/domain/PostContent.java b/src/main/java/com/mallang/post/domain/PostContent.java
index fd44455e..b36db7f8 100644
--- a/src/main/java/com/mallang/post/domain/PostContent.java
+++ b/src/main/java/com/mallang/post/domain/PostContent.java
@@ -58,14 +58,22 @@ public PostContent(
             Member writer
     ) {
         this.title = title;
-        this.postIntro = new PostIntro(postIntro);
         this.bodyText = bodyText;
         this.postThumbnailImageName = postThumbnailImageName;
         this.writer = writer;
+        setPostIntro(postIntro, bodyText);
         setPostCategory(category);
         setTags(tags);
     }
 
+    private void setPostIntro(String postIntro, String bodyText) {
+        if (postIntro == null || postIntro.isBlank()) {
+            this.postIntro = new PostIntro(bodyText.substring(0, Math.min(150, bodyText.length())));
+            return;
+        }
+        this.postIntro = new PostIntro(postIntro);
+    }
+
     private void setPostCategory(@Nullable PostCategory category) {
         if (category == null) {
             this.category = null;
diff --git a/src/main/java/com/mallang/post/domain/PostIntro.java b/src/main/java/com/mallang/post/domain/PostIntro.java
index d3d2c9cb..21a1cec3 100644
--- a/src/main/java/com/mallang/post/domain/PostIntro.java
+++ b/src/main/java/com/mallang/post/domain/PostIntro.java
@@ -13,7 +13,7 @@
 @Embeddable
 public class PostIntro {
 
-    @Column(nullable = false, length = 250)
+    @Column(nullable = false, length = 150)
     private String intro;
 
     public PostIntro(String intro) {
@@ -26,7 +26,7 @@ private void validateLength(String value) {
             throw new InvalidPostIntroLengthException();
         }
         int length = value.strip().length();
-        if (length < 1 || 250 < length) {
+        if (length < 1 || 150 < length) {
             throw new InvalidPostIntroLengthException();
         }
     }
diff --git a/src/main/java/com/mallang/post/presentation/request/CreateDraftRequest.java b/src/main/java/com/mallang/post/presentation/request/CreateDraftRequest.java
index ef9073ca..61cd7927 100644
--- a/src/main/java/com/mallang/post/presentation/request/CreateDraftRequest.java
+++ b/src/main/java/com/mallang/post/presentation/request/CreateDraftRequest.java
@@ -7,7 +7,7 @@
 public record CreateDraftRequest(
         String blogName,
         String title,
-        String intro,
+        @Nullable String intro,
         String bodyText,
         @Nullable String postThumbnailImageName,
         @Nullable Long categoryId,
diff --git a/src/main/java/com/mallang/post/presentation/request/CreatePostRequest.java b/src/main/java/com/mallang/post/presentation/request/CreatePostRequest.java
index 9f600652..38b19cc8 100644
--- a/src/main/java/com/mallang/post/presentation/request/CreatePostRequest.java
+++ b/src/main/java/com/mallang/post/presentation/request/CreatePostRequest.java
@@ -8,7 +8,7 @@
 public record CreatePostRequest(
         String blogName,
         String title,
-        String intro,
+        @Nullable String intro,
         String bodyText,
         @Nullable String postThumbnailImageName,
         Visibility visibility,
diff --git a/src/main/java/com/mallang/post/presentation/request/UpdateDraftRequest.java b/src/main/java/com/mallang/post/presentation/request/UpdateDraftRequest.java
index cab45171..3b90a81f 100644
--- a/src/main/java/com/mallang/post/presentation/request/UpdateDraftRequest.java
+++ b/src/main/java/com/mallang/post/presentation/request/UpdateDraftRequest.java
@@ -6,7 +6,7 @@
 
 public record UpdateDraftRequest(
         String title,
-        String intro,
+        @Nullable String intro,
         String bodyText,
         @Nullable String postThumbnailImageName,
         @Nullable Long categoryId,
diff --git a/src/main/java/com/mallang/post/presentation/request/UpdatePostRequest.java b/src/main/java/com/mallang/post/presentation/request/UpdatePostRequest.java
index 4e93a92a..14f20b45 100644
--- a/src/main/java/com/mallang/post/presentation/request/UpdatePostRequest.java
+++ b/src/main/java/com/mallang/post/presentation/request/UpdatePostRequest.java
@@ -8,7 +8,7 @@
 public record UpdatePostRequest(
         String blogName,
         String title,
-        String intro,
+        @Nullable String intro,
         String bodyText,
         @Nullable String postThumbnailImageName,
         Visibility visibility,
diff --git a/src/test/java/com/mallang/common/infra/s3/PresignedUrlServiceTest.java b/src/test/java/com/mallang/common/infra/s3/PresignedUrlServiceTest.java
index 65fe6e52..9a9f5dd6 100644
--- a/src/test/java/com/mallang/common/infra/s3/PresignedUrlServiceTest.java
+++ b/src/test/java/com/mallang/common/infra/s3/PresignedUrlServiceTest.java
@@ -51,7 +51,7 @@ class PresignedUrlServiceTest {
                 "https://mallang-bucket.s3.amazonaws.com/",
                 "images/" + response.imageName(),
                 ".img",
-                "X-Amz-Expires=" + 60 * 10
+                "X-Amz-Expires="
         );
     }
 }
diff --git a/src/test/java/com/mallang/post/domain/PostContentTest.java b/src/test/java/com/mallang/post/domain/PostContentTest.java
index e3464f5b..c5463250 100644
--- a/src/test/java/com/mallang/post/domain/PostContentTest.java
+++ b/src/test/java/com/mallang/post/domain/PostContentTest.java
@@ -31,6 +31,34 @@ class PostContentTest {
     private final PostCategory jpaPostCategory = 하위_카테고리("JPA", mallang, blog, springPostCategory);
     private final PostCategory otherPostCategory = 루트_카테고리("Spring", otherMember, otherBlog);
 
+    @Test
+    void 인트로가_없으면_본문에서_가져와_설정된다() {
+        // when
+        PostContent postContent = PostContent.builder()
+                .title("제목")
+                .bodyText("내용")
+                .writer(mallang)
+                .build();
+
+        // then
+        String postIntro = postContent.getPostIntro();
+        assertThat(postIntro).isEqualTo("내용");
+    }
+
+    @Test
+    void 인트로가_없을때_본문이_150자_이상이면_150자만_인트로로_설정된다() {
+        // when
+        PostContent postContent = PostContent.builder()
+                .title("제목")
+                .bodyText("1".repeat(151))
+                .writer(mallang)
+                .build();
+
+        // then
+        String postIntro = postContent.getPostIntro();
+        assertThat(postIntro.length()).isEqualTo(150);
+    }
+
     @Test
     void 카테고리를_없앨_수_있다() {
         // given
diff --git a/src/test/java/com/mallang/post/domain/PostIntroTest.java b/src/test/java/com/mallang/post/domain/PostIntroTest.java
index 8ff7ec98..5fca550e 100644
--- a/src/test/java/com/mallang/post/domain/PostIntroTest.java
+++ b/src/test/java/com/mallang/post/domain/PostIntroTest.java
@@ -18,13 +18,13 @@
 class PostIntroTest {
 
     @Test
-    void 길이는_1글자_이상_250_글자_이하여야_한다() {
+    void 길이는_1글자_이상_150_글자_이하여야_한다() {
         // when & then
         assertDoesNotThrow(() -> {
             new PostIntro("1");
         });
         assertDoesNotThrow(() -> {
-            new PostIntro("1".repeat(250));
+            new PostIntro("1".repeat(150));
         });
     }
 
@@ -38,9 +38,9 @@ class PostIntroTest {
     }
 
     @Test
-    void 길익가_250글자_초과라면_예외() {
+    void 길익가_150글자_초과라면_예외() {
         // given
-        String repeat = "1".repeat(251);
+        String repeat = "1".repeat(151);
 
         // when & then
         assertThatThrownBy(() -> {
diff --git a/src/test/java/com/study/StringTest.java b/src/test/java/com/study/StringTest.java
new file mode 100644
index 00000000..2ee0f5ba
--- /dev/null
+++ b/src/test/java/com/study/StringTest.java
@@ -0,0 +1,20 @@
+package com.study;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class StringTest {
+
+    @Test
+    void substring() {
+        // given
+        String str = "1".repeat(200);
+
+        // when
+        String result = str.substring(0, 150);
+
+        // then
+        assertThat(result.length()).isEqualTo(150);
+    }
+}