diff --git a/src/main/java/com/writon/admin/domain/controller/ParticipationController.java b/src/main/java/com/writon/admin/domain/controller/ParticipationController.java
index 0343ab8..2c86f9b 100644
--- a/src/main/java/com/writon/admin/domain/controller/ParticipationController.java
+++ b/src/main/java/com/writon/admin/domain/controller/ParticipationController.java
@@ -3,6 +3,8 @@
 import com.writon.admin.domain.entity.lcoal.ParticipationInfo;
 import com.writon.admin.domain.service.EmailService;
 import com.writon.admin.domain.service.ParticipationService;
+import com.writon.admin.global.error.CustomException;
+import com.writon.admin.global.error.ErrorCode;
 import com.writon.admin.global.response.SuccessDto;
 import java.util.List;
 import lombok.RequiredArgsConstructor;
@@ -53,13 +55,16 @@ public SuccessDto<List<String>> participate(
       @RequestParam Long challengeId,
       @RequestBody List<String> emailList
   ) {
+    if (!participationService.isParticipated(challengeId, emailList)) {
+      List<String> sendedEmailList = participationService.participate(
+          challengeId,
+          emailList
+      );
 
-    List<String> sendedEmailList = participationService.participate(
-        challengeId,
-        emailList
-    );
-
-    return new SuccessDto<>(sendedEmailList);
+      return new SuccessDto<>(sendedEmailList);
+    } else {
+      throw new CustomException(ErrorCode.EMAIL_DUPLICATION);
+    }
   }
 
 
diff --git a/src/main/java/com/writon/admin/domain/service/ParticipationService.java b/src/main/java/com/writon/admin/domain/service/ParticipationService.java
index b5cc913..4c28d80 100644
--- a/src/main/java/com/writon/admin/domain/service/ParticipationService.java
+++ b/src/main/java/com/writon/admin/domain/service/ParticipationService.java
@@ -16,10 +16,13 @@
 import com.writon.admin.global.error.CustomException;
 import com.writon.admin.global.error.ErrorCode;
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.stream.Collectors;
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Service;
+import software.amazon.awssdk.services.s3.endpoints.internal.Value.Bool;
 
 @Service
 @RequiredArgsConstructor
@@ -126,4 +129,19 @@ public List<String> participate(Long challengeId, List<String> emailList) {
 
     return sendedEmailList.stream().map(Email::getEmail).toList();
   }
+
+  public Boolean isParticipated(Long challengeId, List<String> emailList) {
+    List<String> participatedEmailList = getEmailList(challengeId);
+
+    // EmailList를 Set으로 변환하여 검색 속도 향상
+    Set<String> participatedEmailSet = new HashSet<>(participatedEmailList);
+
+    for (String email : emailList) {
+      if (participatedEmailSet.contains(email)) {
+        return true;
+      }
+    }
+
+    return false;
+  }
 }
diff --git a/src/main/java/com/writon/admin/global/config/RedisConfig.java b/src/main/java/com/writon/admin/global/config/RedisConfig.java
index c0440c6..2052fa2 100644
--- a/src/main/java/com/writon/admin/global/config/RedisConfig.java
+++ b/src/main/java/com/writon/admin/global/config/RedisConfig.java
@@ -1,24 +1,17 @@
 package com.writon.admin.global.config;
 
-import com.writon.admin.domain.repository.token.RefreshTokenRepository;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.cache.annotation.EnableCaching;
 import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.context.annotation.FilterType;
 import org.springframework.data.redis.connection.RedisConnectionFactory;
 import org.springframework.data.redis.connection.RedisStandaloneConfiguration;
 import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;
 import org.springframework.data.redis.core.RedisTemplate;
-import org.springframework.data.redis.repository.configuration.EnableRedisRepositories;
 import org.springframework.data.redis.serializer.StringRedisSerializer;
 
 @Configuration
 @EnableCaching
-@EnableRedisRepositories(basePackages = "com.writon.admin.domain.repository.token",
-    includeFilters = @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE,
-        classes = {RefreshTokenRepository.class}))
 public class RedisConfig {
 
   @Value("${spring.data.redis.host}")
diff --git a/src/main/java/com/writon/admin/global/error/ErrorCode.java b/src/main/java/com/writon/admin/global/error/ErrorCode.java
index caa8a8a..2d7f7f2 100644
--- a/src/main/java/com/writon/admin/global/error/ErrorCode.java
+++ b/src/main/java/com/writon/admin/global/error/ErrorCode.java
@@ -30,7 +30,10 @@ public enum ErrorCode {
   ORGANIZATION_NOT_FOUND(HttpStatus.NOT_FOUND, "O01", "조직 정보를 찾을 수 없습니다"),
 
   // challenge
-  CHALLENGE_NOT_FOUND(HttpStatus.NOT_FOUND, "C01", "챌린지 정보를 찾을 수 없습니다");
+  CHALLENGE_NOT_FOUND(HttpStatus.NOT_FOUND, "C01", "챌린지 정보를 찾을 수 없습니다"),
+
+  // participation
+  EMAIL_DUPLICATION(HttpStatus.BAD_REQUEST, "P01", "중복되는 이메일이 존재합니다");
 
   private final HttpStatus httpStatus;
   private final String code;