diff --git a/src/main/java/aromanticcat/umcproject/controller/NangmanLetterController.java b/src/main/java/aromanticcat/umcproject/controller/NangmanLetterController.java
new file mode 100644
index 0000000..9224798
--- /dev/null
+++ b/src/main/java/aromanticcat/umcproject/controller/NangmanLetterController.java
@@ -0,0 +1,36 @@
+package aromanticcat.umcproject.controller;
+
+import aromanticcat.umcproject.apiPayload.ApiResponse;
+import aromanticcat.umcproject.dto.NangmanLetterDTO;
+import aromanticcat.umcproject.service.NangmanLetterService;
+import io.swagger.annotations.ApiOperation;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/nangman-post")
+@RequiredArgsConstructor
+public class NangmanLetterController {
+
+    private final NangmanLetterService nangmanLetterService;
+
+    @PostMapping("/send")
+    @ApiOperation(value = "낭만 우편함 편지 등록")
+    public ApiResponse<NangmanLetterDTO> send(@RequestBody NangmanLetterDTO nangmanLetterDTO){
+        try{
+            //낭만 우편함 편지 작성 및 응답 DTO 변환
+            NangmanLetterDTO responseDTO  = nangmanLetterService.register(nangmanLetterDTO);
+
+            //전송 성공 응답 반환
+            return ApiResponse.onSuccess(responseDTO);
+
+        }catch (Exception e){
+            //에러 발생 시 실패 응답 반환
+            return ApiResponse.onFailure(HttpStatus.INTERNAL_SERVER_ERROR.toString(), e.getMessage(), null);
+        }
+    }
+}
diff --git a/src/main/java/aromanticcat/umcproject/dto/NangmanLetterDTO.java b/src/main/java/aromanticcat/umcproject/dto/NangmanLetterDTO.java
new file mode 100644
index 0000000..a161783
--- /dev/null
+++ b/src/main/java/aromanticcat/umcproject/dto/NangmanLetterDTO.java
@@ -0,0 +1,45 @@
+package aromanticcat.umcproject.dto;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import javax.validation.constraints.NotNull;
+
+@Data
+@Builder
+@AllArgsConstructor
+@NoArgsConstructor
+public class NangmanLetterDTO {
+
+    @NotNull
+    private Long id;
+
+    @NotNull(message = "sender_nickname은 null일 수 없습니다.")
+    private String sender_nickname;
+
+    @NotNull(message = "is_public는 null일 수 없습니다.")
+    private Boolean is_public;
+
+    @NotNull(message = "content는 null일 수 없습니다.")
+    private String content;
+
+    @Builder.Default
+    private Boolean has_response = false;
+
+    private Integer thumbs_up_cnt;
+
+    private Integer heart_cnt;
+
+    private Integer crying_cnt;
+
+    private Integer clover_cnt;
+
+    private Integer clap_cnt;
+
+    private Integer star_cnt;
+
+    @NotNull(message = "member는 null일 수 없습니다.")
+    private Long member_id;
+}
diff --git a/src/main/java/aromanticcat/umcproject/service/NangmanLetterService.java b/src/main/java/aromanticcat/umcproject/service/NangmanLetterService.java
new file mode 100644
index 0000000..84e2df0
--- /dev/null
+++ b/src/main/java/aromanticcat/umcproject/service/NangmanLetterService.java
@@ -0,0 +1,12 @@
+package aromanticcat.umcproject.service;
+
+import aromanticcat.umcproject.dto.NangmanLetterDTO;
+
+public interface NangmanLetterService {
+
+    NangmanLetterDTO register(NangmanLetterDTO nangmanLetterDTO);
+
+    NangmanLetterDTO readOne(Long id);
+
+    void receivedReply(NangmanLetterDTO nangmanLetterDTO);
+}
diff --git a/src/main/java/aromanticcat/umcproject/service/NangmanLetterServiceImpl.java b/src/main/java/aromanticcat/umcproject/service/NangmanLetterServiceImpl.java
new file mode 100644
index 0000000..6dd28c0
--- /dev/null
+++ b/src/main/java/aromanticcat/umcproject/service/NangmanLetterServiceImpl.java
@@ -0,0 +1,79 @@
+package aromanticcat.umcproject.service;
+
+import aromanticcat.umcproject.dto.NangmanLetterDTO;
+import aromanticcat.umcproject.entity.NangmanLetter;
+import aromanticcat.umcproject.repository.MemberRepository;
+import aromanticcat.umcproject.repository.NangmanLetterRepository;
+import lombok.RequiredArgsConstructor;
+import org.modelmapper.ModelMapper;
+import org.springframework.stereotype.Service;
+
+import javax.transaction.Transactional;
+import java.util.Optional;
+
+@Service
+@RequiredArgsConstructor
+@Transactional
+public class NangmanLetterServiceImpl implements NangmanLetterService{
+
+    private final ModelMapper modelMapper;
+    private final NangmanLetterRepository nangmanLetterRepository;
+    private final MemberRepository memberRepository;
+    private final RandomNicknameService randomNicknameService;
+
+    @Override
+    public NangmanLetterDTO register(NangmanLetterDTO nangmanLetterDTO){
+
+        // 랜덤 닉네임 생성
+        String randomNickname = randomNicknameService.generateRandomNickname();
+
+        // DTO에 랜덤 닉네임 설정
+        nangmanLetterDTO.setSender_nickname(randomNickname);
+
+        // DTO를 엔티티로 변환
+        NangmanLetter nangmanLetter = modelMapper.map(nangmanLetterDTO, NangmanLetter.class);
+
+        // 엔티티 저장
+        Long id = nangmanLetterRepository.save(nangmanLetter).getId();
+
+        nangmanLetterDTO.setId(id);
+
+        return nangmanLetterDTO;
+    }
+
+    @Override
+    public NangmanLetterDTO readOne(Long id){
+
+        Optional<NangmanLetter> result = nangmanLetterRepository.findById(id);
+
+        NangmanLetter nangmanLetter = result.orElseThrow();
+
+        NangmanLetterDTO nangmanLetterDTO = modelMapper.map(nangmanLetter, NangmanLetterDTO.class);
+
+        return nangmanLetterDTO;
+    }
+
+
+
+    //답장 받을 때 has_response 업데이트
+    @Override
+    public void receivedReply(NangmanLetterDTO nangmanLetterDTO) {
+        Optional<NangmanLetter> result = nangmanLetterRepository.findById(nangmanLetterDTO.getId());
+
+        NangmanLetter nangmanLetter = result.orElseThrow();
+
+        //has_response 값 업데이트
+        nangmanLetter.change(nangmanLetterDTO.getHas_response());
+
+        //is_public 값에 따라 낭만 모음집에 추가
+        if(nangmanLetter.getIs_public()){
+            addLetterToNangmanCollectoin(nangmanLetter);
+        }
+        nangmanLetterRepository.save(nangmanLetter);
+    }
+
+    private void addLetterToNangmanCollectoin(NangmanLetter nangmanLetter){
+        // 낭만 모음집에 해당 편지를 추가하는 로직을 구현
+        // 추가되는 방법은 해당 모음집의 컬렉션에 편지를 추가하거나 다른 적절한 방법으로 구현
+    }
+}
diff --git a/src/main/java/aromanticcat/umcproject/service/RandomNicknameService.java b/src/main/java/aromanticcat/umcproject/service/RandomNicknameService.java
new file mode 100644
index 0000000..be0b163
--- /dev/null
+++ b/src/main/java/aromanticcat/umcproject/service/RandomNicknameService.java
@@ -0,0 +1,33 @@
+package aromanticcat.umcproject.service;
+
+import org.springframework.stereotype.Service;
+
+import java.util.Random;
+
+@Service
+public class RandomNicknameService {
+
+    private static final String[] ADJECTIVES = {
+            "이야기를 나누는", "그림을 그리는", "창문 너머를 보는", "뒤척이는", "별빛을 따라 떠나는", "달콤한 꿈을 꾸는", "손에 쥐는",
+            "어깨에 기대는", "길을 걷는", "노래하는", "햇살을 받는", "책을 읽는", "쇼핑을 하는", "생각에 잠긴", "향기에 취하는", "바람에 실려 오는",
+            "바다를 바라보는", "눈을 감고 듣는", "손을 흔드는", "입술에 미소 지어지는", "흰 구름을 따라", "옛 추억에 빠진", "노을을 바라보는",
+            "별들을 세는", "사진을 찍는", "운전하는", "손에 든 커피맛이 나는", "열쇠를 꽂는", "무엇인가를 찾는", "일기를 쓰는", "구름 사이를 걷는",
+            "친구에게 전화하는", "빗소리를 듣는", "높은 곳을 내려다보는", "모자를 쓴", "새로운 일을 기대하는", "유쾌한 이야기를 나누는", "햇볕에 담근",
+            "색다른 맛을 느끼는", "머릿결에 바람이 스치는", "두 손에 꽃을 든", "몽환적인 햇살에 비친", "달콤한 미소를 띤", "꿈결처럼 가벼운", "가슴에 품은",
+            "순수한 눈으로 보는", "바닷가를 걷는", "강을 건너는", "별빛이 내리는", "작은 행복을 쌓는"
+    };
+
+    private static final String[] ANIMALS = {
+            "알파카", "토끼", "햄스터", "고슴도치", "판다", "코알라", "산토끼", "레서 판다", "푸들", "기니피그", "레서캣",
+            "물개", "비둘기", "고양이", "강아지", "병아리", "쿼카", "펭귄", "오소리", "개구리", "반달곰", "부엉이", "아기 곰", "거북이",
+            "오리", "나비", "올빼미", "여우", "수달", "파랑새", "황제 펭귄", "호랑이", "해달", "자라", "아기 돼지", "백조"
+    };
+
+    public String generateRandomNickname() {
+        Random random = new Random();
+        String adjective = ADJECTIVES[random.nextInt(ADJECTIVES.length)];
+        String animal = ANIMALS[random.nextInt(ANIMALS.length)]
+                ;
+        return adjective + " " + animal;
+    }
+}
diff --git a/src/test/java/aromanticcat/umcproject/service/NangmanLetterServiceTests.java b/src/test/java/aromanticcat/umcproject/service/NangmanLetterServiceTests.java
new file mode 100644
index 0000000..fa86d31
--- /dev/null
+++ b/src/test/java/aromanticcat/umcproject/service/NangmanLetterServiceTests.java
@@ -0,0 +1,53 @@
+package aromanticcat.umcproject.service;
+
+import aromanticcat.umcproject.repository.MemberRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+public class NangmanLetterServiceTests {
+
+    @Autowired
+    private NangmanLetterService nangmanLetterService;
+
+    @Autowired
+    private MemberRepository memberRepository;
+
+    @Autowired
+    private RandomNicknameService randomNicknameService;
+
+//    @Test
+//    public void testRegister(){
+//        System.out.println(nangmanLetterService.getClass().getName());
+//
+//        Member member1 = memberRepository.findById(1L).orElseThrow(() -> new RuntimeException("Member not found"));
+//
+//        //랜덤 닉네임 생성
+//        String randomNickname = randomNicknameService.generateRandomNickname();
+//
+//        NangmanLetterDTO nangmanLetterDTO = NangmanLetterDTO.builder()
+//                .content("낭만 편지 샘플3")
+//                .is_public(false)
+//                .member(member1)
+//                .build();
+//
+//        //생성된 랜덤 닉네임 설정
+//        nangmanLetterDTO.setSender_nickname(randomNickname);
+//
+//        Long id = nangmanLetterService.register(nangmanLetterDTO);
+//
+//        System.out.println("id: " + id);
+//    }
+
+//    @Test
+//    public void testModify(){
+//
+//        //변경에 필요한 데이터만
+//        NangmanLetterDTO nangmanLetterDTO = NangmanLetterDTO.builder()
+//                .id(4L)
+//                .has_response(true)
+//                .build();
+//
+//        nangmanLetterService.modify(nangmanLetterDTO);
+//    }
+}