diff --git a/src/controllers/participations.controller.ts b/src/controllers/participations.controller.ts
index 60e2bbf..fb035cf 100644
--- a/src/controllers/participations.controller.ts
+++ b/src/controllers/participations.controller.ts
@@ -1,4 +1,12 @@
-import { Body, Controller, Post } from "@nestjs/common";
+import {
+    Body,
+    Controller,
+    Delete,
+    Get,
+    NotFoundException,
+    Param,
+    Post,
+} from "@nestjs/common";
 
 import { CurrentMemberDecorator } from "@APP/common/decorators/current-member.decorator";
 import { CreateParticipationDto } from "@APP/dtos/create-participation.dto";
@@ -12,6 +20,23 @@ export class ParticipationsController {
         private readonly articlesService: ArticlesService,
     ) {}
 
+    @Get(":participationId")
+    async getParticipation(
+        @Param("participationId") participationId: number,
+        @CurrentMemberDecorator("id") currentMemberId: number,
+    ) {
+        const participation = await this.participationsService.getParticipation(
+            participationId,
+            currentMemberId,
+        );
+
+        if (!participation) {
+            throw new NotFoundException("참여 정보를 찾을 수 없습니다.");
+        }
+
+        return participation;
+    }
+
     @Post()
     async postParticipation(
         @Body() body: CreateParticipationDto,
@@ -24,4 +49,15 @@ export class ParticipationsController {
             body,
         );
     }
+
+    @Delete(":participationId")
+    async deleteParticipation(
+        @Param("participationId") participationId: number,
+        @CurrentMemberDecorator("id") currentMemberId: number,
+    ) {
+        return await this.participationsService.deleteParticipation(
+            participationId,
+            currentMemberId,
+        );
+    }
 }
diff --git a/src/services/participations.service.ts b/src/services/participations.service.ts
index 16f86a1..cf502a7 100644
--- a/src/services/participations.service.ts
+++ b/src/services/participations.service.ts
@@ -1,5 +1,10 @@
-import { Injectable } from "@nestjs/common";
+import {
+    ConflictException,
+    Injectable,
+    NotFoundException,
+} from "@nestjs/common";
 
+import { ParticipationStatus } from "@APP/common/enum/participation-status.enum";
 import { CreateParticipationDto } from "@APP/dtos/create-participation.dto";
 import { ParticipationRepository } from "@APP/repositories/participation.repository";
 
@@ -9,25 +14,79 @@ export class ParticipationsService {
         private readonly participationsRepository: ParticipationRepository,
     ) {}
 
+    async getParticipation(participationId: number, currentMemberId: number) {
+        return await this.participationsRepository.findOne({
+            where: { id: participationId, memberId: currentMemberId },
+        });
+    }
+
     async createParticipation(
         currentMemberId: number,
         body: CreateParticipationDto,
     ) {
-        const newParticipation = this.createParticipationEntity(
-            currentMemberId,
-            body,
-        );
+        const participation = await this.participationsRepository.findOne({
+            where: {
+                memberId: currentMemberId,
+                articleId: body.articleId,
+            },
+        });
+
+        if (!participation) {
+            const newParticipation = this.createParticipationEntity(
+                currentMemberId,
+                body,
+            );
+
+            return await this.participationsRepository.save(newParticipation);
+        }
+
+        if (participation.status === ParticipationStatus.CANCELLED) {
+            const updatedParticipation = this.createParticipationEntity(
+                currentMemberId,
+                body,
+                ParticipationStatus.ACTIVE,
+            );
+
+            return await this.participationsRepository.save(
+                updatedParticipation,
+            );
+        }
 
-        return await this.participationsRepository.save(newParticipation);
+        throw new ConflictException("이미 참여한 게시글입니다.");
     }
 
     private createParticipationEntity(
         currentMemberId: number,
         body: CreateParticipationDto,
+        status?: ParticipationStatus,
     ) {
         return this.participationsRepository.create({
             memberId: currentMemberId,
             ...body,
+            status,
         });
     }
+
+    async deleteParticipation(
+        participationId: number,
+        currentMemberId: number,
+    ) {
+        const participation = await this.participationsRepository.findOne({
+            where: { id: participationId, memberId: currentMemberId },
+        });
+
+        if (!participation) {
+            throw new NotFoundException("참여 정보를 찾을 수 없습니다.");
+        }
+
+        await this.participationsRepository.update(
+            {
+                id: participationId,
+                memberId: currentMemberId,
+            },
+            {
+                status: ParticipationStatus.CANCELLED,
+            },
+        );
+    }
 }