diff --git a/src/main/java/com/devin/dev/controller/reply/ReplyController.java b/src/main/java/com/devin/dev/controller/reply/ReplyController.java
index 5d7992c..395d12e 100644
--- a/src/main/java/com/devin/dev/controller/reply/ReplyController.java
+++ b/src/main/java/com/devin/dev/controller/reply/ReplyController.java
@@ -42,6 +42,11 @@ public DefaultResponse<?> changePostLike(@PathVariable("id") Long replyId, HttpS
         return replyService.changeReplyLike(replyId, request);
     }
 
+    @PatchMapping("/reply/{id}/select")
+    public DefaultResponse<?> selectReply(@PathVariable("id") Long replyId, HttpServletRequest request) {
+        return replyService.selectReply(replyId, request);
+    }
+
     @Data
     private static class CreateReplyResponse {
         private Long id;
diff --git a/src/main/java/com/devin/dev/service/ReplyService.java b/src/main/java/com/devin/dev/service/ReplyService.java
index a90cd62..cd4e558 100644
--- a/src/main/java/com/devin/dev/service/ReplyService.java
+++ b/src/main/java/com/devin/dev/service/ReplyService.java
@@ -6,6 +6,7 @@
 import com.devin.dev.dto.reply.ReplyLikeDto;
 import com.devin.dev.dto.reply.ReplyMapper;
 import com.devin.dev.entity.post.Post;
+import com.devin.dev.entity.post.PostStatus;
 import com.devin.dev.entity.reply.Reply;
 import com.devin.dev.entity.reply.ReplyImage;
 import com.devin.dev.entity.reply.ReplyLike;
@@ -393,4 +394,48 @@ public DefaultResponse<ReplyDto> changeReplyLike(Long replyId, HttpServletReques
 
         return new DefaultResponse<>(StatusCode.SUCCESS, ResponseMessage.REPLY_LIKE_CHANGE_SUCCESS, replyDto);
     }
+
+    public DefaultResponse<?> selectReply(Long replyId, HttpServletRequest request) {
+        String token = tokenProvider.parseToken(request);
+        Long userId;
+        if (tokenProvider.validateToken(token)) {
+            userId = tokenProvider.getUserId(token);
+        } else {
+            return new DefaultResponse<>(StatusCode.FAIL_AUTH, ResponseMessage.NOT_FOUND_USER);
+        }
+        Optional<User> userOptional = userRepository.findById(userId);
+        if (userOptional.isEmpty()) {
+            return new DefaultResponse<>(StatusCode.NOT_EXIST, ResponseMessage.NOT_FOUND_USER);
+        }
+        User user = userOptional.get();
+
+        Optional<Reply> replyOptional = replyRepository.findById(replyId);
+        if (replyOptional.isEmpty()) {
+            return new DefaultResponse<>(StatusCode.NOT_EXIST, ResponseMessage.NOT_FOUND_REPLY);
+        }
+        Reply reply = replyOptional.get();
+
+        if (isNotSameUser(user, reply.getPost().getUser())) {
+            return new DefaultResponse<>(StatusCode.CONDITION_FAIL, ResponseMessage.NOT_SAME_USER);
+        }
+
+        if (user.getId().equals(reply.getUser().getId())) {
+            return new DefaultResponse<>(StatusCode.CONDITION_FAIL, ResponseMessage.SAME_USER);
+        }
+
+        user.changeExp(User.ExpChangeType.REPLY_SELECT);
+        reply.getUser().changeExp(User.ExpChangeType.REPLY_BE_SELECTED);
+
+        reply.setStatus(ReplyStatus.SELECTED);
+        reply.getPost().setStatus(PostStatus.SELECTED);
+
+        replyRepository.save(reply);
+        userRepository.save(user);
+        userRepository.save(reply.getUser());
+        postRepository.save(reply.getPost());
+
+        ReplyDto replyDto = new ReplyDto(reply);
+
+        return new DefaultResponse<>(StatusCode.SUCCESS, ResponseMessage.REPLY_LIKE_CHANGE_SUCCESS, replyDto);
+    }
 }
diff --git a/src/main/java/com/devin/dev/utils/ResponseMessage.java b/src/main/java/com/devin/dev/utils/ResponseMessage.java
index 024bb69..05ebaf0 100644
--- a/src/main/java/com/devin/dev/utils/ResponseMessage.java
+++ b/src/main/java/com/devin/dev/utils/ResponseMessage.java
@@ -12,6 +12,7 @@ public enum ResponseMessage {
     NOT_FOUND_REPLY("답변을 찾을 수 없습니다."),
     NOT_FOUND_SUBJECT("주제를 찾을 수 없습니다."),
     NOT_SAME_USER("작성자가 아닙니다."),
+    SAME_USER("작성자 입니다."),
     CANNOT_DELETE_SELECTED("채택된 답변은 삭제할 수 없습니다."),
     CREATED_USER("회원 가입 성공"),
     UPDATE_USER("회원 정보 수정 성공"),