diff --git a/backend/src/main/java/org/sejongisc/backend/attendance/controller/AttendanceSessionController.java b/backend/src/main/java/org/sejongisc/backend/attendance/controller/AttendanceSessionController.java
index 6a5b82b9..c329bec9 100644
--- a/backend/src/main/java/org/sejongisc/backend/attendance/controller/AttendanceSessionController.java
+++ b/backend/src/main/java/org/sejongisc/backend/attendance/controller/AttendanceSessionController.java
@@ -14,6 +14,7 @@
 import org.sejongisc.backend.common.auth.dto.CustomUserDetails;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
 import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.GetMapping;
@@ -245,4 +246,28 @@ public ResponseEntity<Void> deleteSession(
     attendanceSessionService.deleteSession(sessionId, adminUserId);
     return ResponseEntity.ok().build();
   }
-}
+
+  /**
+   * 정규 세션 용 전체 회원 넣는 API(회장용)
+   */
+
+  @Operation(
+      summary = "정규세션에 active 상태인 전체 회원 추가",
+      description = """
+          ## 인증(JWT): **필요**
+          
+          ## 요청 파라미터 ( `sessionId` )
+          
+          ## 회장이면서 세션의 장이어야만 가능
+          """
+  )
+  @PostMapping("/{sessionId}/add-all-users")
+  @PreAuthorize("hasRole('PRESIDENT')")
+  public ResponseEntity<Void> addAllUsers(
+      @PathVariable UUID sessionId,
+      @AuthenticationPrincipal CustomUserDetails userDetails
+  ) {
+    UUID adminUserId = requireUserId(userDetails);
+    attendanceSessionService.addAllUsers(sessionId, adminUserId);
+    return ResponseEntity.ok().build();
+}}
diff --git a/backend/src/main/java/org/sejongisc/backend/attendance/repository/SessionUserRepository.java b/backend/src/main/java/org/sejongisc/backend/attendance/repository/SessionUserRepository.java
index be5b3689..2b3d511d 100644
--- a/backend/src/main/java/org/sejongisc/backend/attendance/repository/SessionUserRepository.java
+++ b/backend/src/main/java/org/sejongisc/backend/attendance/repository/SessionUserRepository.java
@@ -1,5 +1,6 @@
 package org.sejongisc.backend.attendance.repository;
 
+import org.sejongisc.backend.attendance.entity.AttendanceSession;
 import org.sejongisc.backend.attendance.entity.SessionUser;
 import org.sejongisc.backend.user.entity.User;
 import org.springframework.data.jpa.repository.JpaRepository;
@@ -16,6 +17,7 @@
 public interface SessionUserRepository extends JpaRepository<SessionUser, UUID> {
     Optional<SessionUser> findByAttendanceSession_AttendanceSessionIdAndUser_UserId(UUID sessionId, UUID userId);
 
+    boolean existsByAttendanceSessionAndUser(AttendanceSession session, User user);
 
     boolean existsByAttendanceSession_AttendanceSessionIdAndUser_UserId(UUID sessionId, UUID userId);
 
diff --git a/backend/src/main/java/org/sejongisc/backend/attendance/service/AttendanceSessionService.java b/backend/src/main/java/org/sejongisc/backend/attendance/service/AttendanceSessionService.java
index 40639def..c1081b62 100644
--- a/backend/src/main/java/org/sejongisc/backend/attendance/service/AttendanceSessionService.java
+++ b/backend/src/main/java/org/sejongisc/backend/attendance/service/AttendanceSessionService.java
@@ -12,6 +12,7 @@
 import org.sejongisc.backend.attendance.repository.SessionUserRepository;
 import org.sejongisc.backend.common.exception.CustomException;
 import org.sejongisc.backend.common.exception.ErrorCode;
+import org.sejongisc.backend.user.entity.UserStatus;
 import org.sejongisc.backend.user.repository.UserRepository;
 import org.sejongisc.backend.user.entity.User;
 import org.springframework.stereotype.Service;
@@ -152,4 +153,31 @@ public void closeSession(UUID sessionId, UUID userId) {
     attendanceSessionRepository.save(session);
     log.info("출석 세션 종료 완료: 세션ID={}", sessionId);
   }
+
+  public void addAllUsers(UUID sessionId, UUID userId) {
+    // 권한 확인
+    attendanceAuthorizationService.ensureAdmin(sessionId, userId);
+    log.info("세션에 모든 사용자 추가 시작: 세션ID={}", sessionId);
+
+    AttendanceSession session = attendanceSessionRepository.findById(sessionId)
+        .orElseThrow(() -> new CustomException(ErrorCode.SESSION_NOT_FOUND));
+
+    // UserStatus.ACTIVE인 사용자만 추가하도록 수정
+    List<User> allUsers = userRepository.findAllByStatus(UserStatus.ACTIVE);
+
+    for (User user : allUsers) {
+      boolean alreadyAdded = sessionUserRepository.existsByAttendanceSessionAndUser(session, user);
+      if (!alreadyAdded) {
+        SessionUser su = SessionUser.builder()
+            .attendanceSession(session)
+            .user(user)
+            .sessionRole(SessionRole.PARTICIPANT)
+            .build();
+        sessionUserRepository.save(su);
+        log.info("사용자 {} 세션에 추가됨", user.getUserId());
+      }
+    }
+
+    log.info("세션에 모든 사용자 추가 완료: 세션ID={}", sessionId);
+  }
 }
diff --git a/backend/src/main/java/org/sejongisc/backend/user/controller/UserController.java b/backend/src/main/java/org/sejongisc/backend/user/controller/UserController.java
index 173f7379..ca50e006 100644
--- a/backend/src/main/java/org/sejongisc/backend/user/controller/UserController.java
+++ b/backend/src/main/java/org/sejongisc/backend/user/controller/UserController.java
@@ -69,4 +69,4 @@ public ResponseEntity<List<ActivityLog>> getAttendanceLogs(@AuthenticationPrinci
   public ResponseEntity<List<ActivityLog>> getBoardLogs(@AuthenticationPrincipal CustomUserDetails customUserDetails) {
     return ResponseEntity.ok(userService.getBoardActivityLog(customUserDetails.getUserId()));
   }
-}
\ No newline at end of file
+}