diff --git a/src/main/java/side/onetime/repository/EventParticipationRepository.java b/src/main/java/side/onetime/repository/EventParticipationRepository.java
index 94c27f7..6d15e20 100644
--- a/src/main/java/side/onetime/repository/EventParticipationRepository.java
+++ b/src/main/java/side/onetime/repository/EventParticipationRepository.java
@@ -1,19 +1,14 @@
 package side.onetime.repository;
 
 import org.springframework.data.jpa.repository.JpaRepository;
-import org.springframework.data.jpa.repository.Query;
-import org.springframework.data.repository.query.Param;
 import side.onetime.domain.Event;
 import side.onetime.domain.EventParticipation;
 import side.onetime.domain.User;
 
 import java.util.List;
-import java.util.Optional;
 
 public interface EventParticipationRepository extends JpaRepository<EventParticipation,Long> {
     List<EventParticipation> findAllByEvent(Event event);
     List<EventParticipation> findAllByUser(User user);
-    @Query("SELECT COUNT(ep) FROM EventParticipation ep WHERE ep.event = :event")
-    int countByEvent(@Param("event") Event event);
-    Optional<EventParticipation> findByUserAndEvent(User user, Event event);
+    EventParticipation findByUserAndEvent(User user, Event event);
 }
\ No newline at end of file
diff --git a/src/main/java/side/onetime/service/EventService.java b/src/main/java/side/onetime/service/EventService.java
index 7606562..c51fab1 100644
--- a/src/main/java/side/onetime/service/EventService.java
+++ b/src/main/java/side/onetime/service/EventService.java
@@ -129,9 +129,10 @@ public GetEventResponse getEvent(String eventId, String authorizationHeader) {
         EventStatus eventStatus = null;
         if (authorizationHeader != null) {
             User user = jwtUtil.getUserFromHeader(authorizationHeader);
-            EventParticipation eventParticipation = eventParticipationRepository.findByUserAndEvent(user, event)
-                    .orElseThrow(() -> new CustomException(EventParticipationErrorStatus._NOT_FOUND_EVENT_PARTICIPATION));
-            eventStatus = eventParticipation.getEventStatus();
+            EventParticipation eventParticipation = eventParticipationRepository.findByUserAndEvent(user, event);
+            if (eventParticipation != null) {
+                eventStatus = eventParticipation.getEventStatus();
+            }
         }
 
         return GetEventResponse.of(event, ranges, eventStatus);
@@ -308,8 +309,10 @@ public void removeUserCreatedEvent(String authorizationHeader, String eventId) {
         Event event = eventRepository.findByEventId(UUID.fromString(eventId))
                 .orElseThrow(() -> new CustomException(EventErrorStatus._NOT_FOUND_EVENT));
 
-        EventParticipation eventParticipation = eventParticipationRepository.findByUserAndEvent(user, event)
-                .orElseThrow(() -> new CustomException(EventParticipationErrorStatus._NOT_FOUND_EVENT_PARTICIPATION));
+        EventParticipation eventParticipation = eventParticipationRepository.findByUserAndEvent(user, event);
+        if (eventParticipation == null) {
+            throw new CustomException(EventParticipationErrorStatus._NOT_FOUND_EVENT_PARTICIPATION);
+        }
         if (!EventStatus.CREATOR.equals(eventParticipation.getEventStatus())) {
             // 해당 이벤트의 생성자가 아닌 경우
             throw new CustomException(EventParticipationErrorStatus._IS_NOT_USERS_CREATED_EVENT_PARTICIPATION);
diff --git a/src/main/java/side/onetime/service/ScheduleService.java b/src/main/java/side/onetime/service/ScheduleService.java
index cf6c89b..23fc331 100644
--- a/src/main/java/side/onetime/service/ScheduleService.java
+++ b/src/main/java/side/onetime/service/ScheduleService.java
@@ -71,14 +71,16 @@ public void createDaySchedulesForAuthenticatedUser(CreateDayScheduleRequest crea
                 .orElseThrow(() -> new CustomException(EventErrorStatus._NOT_FOUND_EVENT));
         User user = jwtUtil.getUserFromHeader(authorizationHeader);
         // 참여 정보가 없는 경우 참여자로 저장
-        eventParticipationRepository.findByUserAndEvent(user, event)
-                .orElseGet(() -> eventParticipationRepository.save(
-                        EventParticipation.builder()
-                                .user(user)
-                                .event(event)
-                                .eventStatus(EventStatus.PARTICIPANT)
-                                .build()
-                ));
+        EventParticipation eventParticipation = eventParticipationRepository.findByUserAndEvent(user, event);
+        if (eventParticipation == null) {
+            eventParticipationRepository.save(
+                    EventParticipation.builder()
+                            .user(user)
+                            .event(event)
+                            .eventStatus(EventStatus.PARTICIPANT)
+                            .build()
+            );
+        }
 
         List<DaySchedule> daySchedules = createDayScheduleRequest.daySchedules();
         List<Selection> newSelections = new ArrayList<>();
@@ -141,14 +143,16 @@ public void createDateSchedulesForAuthenticatedUser(CreateDateScheduleRequest cr
                 .orElseThrow(() -> new CustomException(EventErrorStatus._NOT_FOUND_EVENT));
         User user = jwtUtil.getUserFromHeader(authorizationHeader);
         // 참여 정보가 없는 경우 참여자로 저장
-        eventParticipationRepository.findByUserAndEvent(user, event)
-                .orElseGet(() -> eventParticipationRepository.save(
-                        EventParticipation.builder()
-                                .user(user)
-                                .event(event)
-                                .eventStatus(EventStatus.PARTICIPANT)
-                                .build()
-                ));
+        EventParticipation eventParticipation = eventParticipationRepository.findByUserAndEvent(user, event);
+        if (eventParticipation == null) {
+            eventParticipationRepository.save(
+                    EventParticipation.builder()
+                            .user(user)
+                            .event(event)
+                            .eventStatus(EventStatus.PARTICIPANT)
+                            .build()
+            );
+        }
 
         List<DateSchedule> dateSchedules = createDateScheduleRequest.dateSchedules();
         List<Selection> newSelections = new ArrayList<>();