diff --git a/src/main/java/org/fastcampus/jober/config/SecurityConfig.java b/src/main/java/org/fastcampus/jober/config/SecurityConfig.java
index 8646f63..f0b5187 100644
--- a/src/main/java/org/fastcampus/jober/config/SecurityConfig.java
+++ b/src/main/java/org/fastcampus/jober/config/SecurityConfig.java
@@ -15,6 +15,7 @@
 import org.springframework.core.Ordered;
 import org.springframework.security.authentication.*;
 import org.springframework.security.authentication.dao.DaoAuthenticationProvider;
+import org.springframework.security.authorization.AuthorizationDecision;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.annotation.web.configurers.AbstractHttpConfigurer;
 import org.springframework.security.config.annotation.web.configurers.HeadersConfigurer;
@@ -132,7 +133,13 @@ public SecurityFilterChain securityFilterChain(
         .headers(headers -> headers.frameOptions(HeadersConfigurer.FrameOptionsConfig::sameOrigin))
         .authorizeHttpRequests(
             auth ->
-                auth.requestMatchers(props.getPermitAll().toArray(String[]::new))
+                auth
+                        .requestMatchers("/register", "/user/register")
+                        .access((authentication, context) -> {
+                            boolean noSession = authentication.get().getPrincipal().equals("anonymousUser");
+                            return new AuthorizationDecision(noSession);
+                        })
+                    .requestMatchers(props.getPermitAll().toArray(String[]::new))
                     .permitAll()
                     .requestMatchers(props.getPermitUser().toArray(String[]::new))
                     .permitAll()
diff --git a/src/main/java/org/fastcampus/jober/space/controller/SpaceMemberController.java b/src/main/java/org/fastcampus/jober/space/controller/SpaceMemberController.java
index 088a682..9cfdbc4 100644
--- a/src/main/java/org/fastcampus/jober/space/controller/SpaceMemberController.java
+++ b/src/main/java/org/fastcampus/jober/space/controller/SpaceMemberController.java
@@ -66,17 +66,14 @@ public ResponseEntity<Void> acceptInvitation(
        return ResponseEntity.ok().build();
     }
 
-  /**
-   * 특정 스페이스의 모든 멤버를 조회합니다.
-   *
-   * @param spaceId 멤버를 조회할 스페이스 ID
-   * @return 스페이스 멤버 목록과 HTTP 상태 코드
-   */
-  @Operation(summary = "스페이스 멤버 조회", description = "특정 spaceId에 속한 모든 멤버 정보를 가져옵니다.")
-  @Parameter(name = "spaceId", description = "멤버를 조회할 스페이스의 ID", required = true)
+    @Operation(summary = "스페이스 멤버 조회", description = "특정 스페이스에 속한 모든 멤버 정보를 조회합니다. 해당 스페이스의 멤버만 조회할 수 있습니다.")
+    @Parameter(name = "spaceId", description = "멤버를 조회할 스페이스의 ID", required = true)
+    @ApiResponse(responseCode = "200", description = "멤버 조회 성공")
+    @ApiResponse(responseCode = "403", description = "해당 스페이스 멤버가 아닌 경우")
   @GetMapping("/{spaceId}/members")
-  public ResponseEntity<List<SpaceMemberListResponseDto>> getSpaceMembers(@PathVariable Long spaceId) {
-    List<SpaceMemberListResponseDto> result = spaceMemberService.getSpaceMembers(spaceId);
+  public ResponseEntity<List<SpaceMemberListResponseDto>> getSpaceMembers(@PathVariable Long spaceId,
+                                                                          @AuthenticationPrincipal CustomUserDetails principal) {
+    List<SpaceMemberListResponseDto> result = spaceMemberService.getSpaceMembers(spaceId, principal);
     return ResponseEntity.ok(result);
   }
 
@@ -161,7 +158,7 @@ public ResponseEntity<List<SpaceMemberListResponseDto>> getMemberByTag(
             @Parameter(hidden = true)
             @AuthenticationPrincipal CustomUserDetails principal
     ) {
-        List<SpaceMemberListResponseDto> result = spaceMemberService.getMemberByTag(spaceId, tag, principal.getUserId());
+        List<SpaceMemberListResponseDto> result = spaceMemberService.getMemberByTag(spaceId, tag, principal);
 
         return ResponseEntity.ok(result);
     }
diff --git a/src/main/java/org/fastcampus/jober/space/dto/InviteStatus.java b/src/main/java/org/fastcampus/jober/space/dto/InviteStatus.java
index 186e9c1..1d41ed6 100644
--- a/src/main/java/org/fastcampus/jober/space/dto/InviteStatus.java
+++ b/src/main/java/org/fastcampus/jober/space/dto/InviteStatus.java
@@ -11,6 +11,7 @@
 import org.fastcampus.jober.space.entity.Space;
 import org.fastcampus.jober.space.entity.SpaceMember;
 import org.fastcampus.jober.user.entity.Users;
+import org.hibernate.annotations.DynamicUpdate;
 
 import java.time.LocalDateTime;
 
@@ -19,6 +20,7 @@
 @Getter
 @NoArgsConstructor
 @AllArgsConstructor
+@DynamicUpdate
 public class InviteStatus extends BaseEntity {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
@@ -48,13 +50,17 @@ public void updateStatus(InviteStatusType status) {
         this.status = status;
     }
 
+    /**
+     * 얘를 SpaceMemberMapper로 옮기면 this.tag, this.authority를 그대로 가져오지 못하는데
+     * SpaceMember toSpaceMember(InviteStatus inviteStatus, Space space, Users user); 처럼 파라미터를 늘리는게 나은지
+     * 아님 지금처럼 이 파일에 두는게 나은지?
+     */
     public SpaceMember toSpaceMember(Space space, Users user) {
         return SpaceMember.builder()
                 .space(space)
                 .user(user)
                 .tag(this.tag)
                 .authority(this.authority)
-                .isDeleted(false)
                 .build();
     }
 }
diff --git a/src/main/java/org/fastcampus/jober/space/entity/Space.java b/src/main/java/org/fastcampus/jober/space/entity/Space.java
index b3773f4..619abe6 100644
--- a/src/main/java/org/fastcampus/jober/space/entity/Space.java
+++ b/src/main/java/org/fastcampus/jober/space/entity/Space.java
@@ -12,12 +12,14 @@
 import org.fastcampus.jober.error.ErrorCode;
 import org.fastcampus.jober.space.dto.request.SpaceUpdateRequestDto;
 import org.fastcampus.jober.user.entity.Users;
+import org.hibernate.annotations.DynamicUpdate;
 
 @Entity
 @Getter
 @NoArgsConstructor
 @AllArgsConstructor
 @Builder
+@DynamicUpdate
 public class Space extends BaseEntity {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
diff --git a/src/main/java/org/fastcampus/jober/space/entity/SpaceMember.java b/src/main/java/org/fastcampus/jober/space/entity/SpaceMember.java
index ab50c49..a332688 100644
--- a/src/main/java/org/fastcampus/jober/space/entity/SpaceMember.java
+++ b/src/main/java/org/fastcampus/jober/space/entity/SpaceMember.java
@@ -9,12 +9,14 @@
 import org.fastcampus.jober.common.entity.BaseEntity;
 import org.fastcampus.jober.space.dto.request.MemberUpdateRequestDto;
 import org.fastcampus.jober.user.entity.Users;
+import org.hibernate.annotations.DynamicUpdate;
 
 @Entity
 @Getter
 @AllArgsConstructor
 @NoArgsConstructor
 @Builder
+@DynamicUpdate
 public class SpaceMember extends BaseEntity {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
@@ -33,8 +35,8 @@ public class SpaceMember extends BaseEntity {
   @JoinColumn(name = "userId")
   private Users user;
 
-  @Column(nullable = false)
-  @Builder.Default
+  @Column(nullable = false)   // DB 스키마의 제약조건
+  @Builder.Default            // 애플리케이션 레벨 기본값
   private Boolean isDeleted = false; // 멤버 논리삭제 유무
 
   public void softDelete() {isDeleted = true;}
diff --git a/src/main/java/org/fastcampus/jober/space/service/SpaceMemberService.java b/src/main/java/org/fastcampus/jober/space/service/SpaceMemberService.java
index f6a8576..b83df6c 100644
--- a/src/main/java/org/fastcampus/jober/space/service/SpaceMemberService.java
+++ b/src/main/java/org/fastcampus/jober/space/service/SpaceMemberService.java
@@ -75,7 +75,7 @@ public InviteResult inviteSpaceMember(Long spaceId, List<SpaceMemberAddRequestDt
       successEmails.add(dto.getEmail());
 
       InviteStatus inviteMember = InviteStatus.builder()
-              .authority(dto.getAuthority())
+              .authority(Authority.MEMBER) // 일단 멤버로만 추가 가능하게 수정
               .tag(dto.getTag())
               .email(dto.getEmail())
               .status(InviteStatusType.PENDING)
@@ -140,7 +140,10 @@ public void processSpaceInvitation(Long spaceId, String email, Users user) {
     spaceMemberRepository.save(spaceMember);
   }
 
-  public List<SpaceMemberListResponseDto> getSpaceMembers(Long spaceId) {
+  public List<SpaceMemberListResponseDto> getSpaceMembers(Long spaceId, CustomUserDetails principal) {
+    spaceMemberRepository.findBySpaceIdAndUserId(spaceId, principal.getUserId())
+            .orElseThrow(() -> new BusinessException(ErrorCode.FORBIDDEN, "해당 스페이스 멤버만 조회할 수 있습니다."));
+
     List<SpaceMember> spaceMembers = spaceMemberRepository.findBySpaceId(spaceId);
     return spaceMemberMapper.toMemberResponseDtoList(spaceMembers);
   }
@@ -155,6 +158,13 @@ public void deleteSpaceMember(List<Long> memberIds, Long spaceId, CustomUserDeta
     if (members.size() != memberIds.size()) {
       throw new BusinessException(ErrorCode.NOT_FOUND, "해당하는 멤버가 없습니다.");}
 
+    boolean containsAdmin = members.stream()
+            .anyMatch(m -> m.getAuthority() == Authority.ADMIN);
+
+    if (containsAdmin) {
+      throw new BusinessException(ErrorCode.BAD_REQUEST, "관리자는 삭제할 수 없습니다.");
+    }
+
     members.forEach(SpaceMember::softDelete);
 
     // 3. 명시적 저장 (혹시 모를 Dirty Checking 문제 방지)
@@ -172,15 +182,12 @@ public MemberUpdateResponseDto updateMember(Long memberId, Long spaceId, MemberU
     return spaceMemberMapper.toMemberUpdateResponseDto(member);
   }
 
-  public List<SpaceMemberListResponseDto> getMemberByTag(Long spaceId, String tag, Long userId) {
-
-    spaceRepository.findByIdOrThrow(spaceId);
-
-    spaceMemberRepository.findBySpaceIdAndUserId(spaceId, userId)
+  public List<SpaceMemberListResponseDto> getMemberByTag(Long spaceId, String tag, CustomUserDetails principal) {
+    spaceMemberRepository.findBySpaceIdAndUserId(spaceId, principal.getUserId())
             .orElseThrow(() -> new BusinessException(ErrorCode.FORBIDDEN, "해당 스페이스 멤버만 조회할 수 있습니다."));
 
+    spaceRepository.findByIdOrThrow(spaceId);
     List<SpaceMember> members = spaceMemberRepository.findBySpaceIdAndTag(spaceId, tag);
-
     return spaceMemberMapper.toMemberResponseDtoList(members);
 
   }
diff --git a/src/main/java/org/fastcampus/jober/space/service/SpaceService.java b/src/main/java/org/fastcampus/jober/space/service/SpaceService.java
index 182cf0d..52d6afb 100644
--- a/src/main/java/org/fastcampus/jober/space/service/SpaceService.java
+++ b/src/main/java/org/fastcampus/jober/space/service/SpaceService.java
@@ -39,7 +39,6 @@ public void createSpace(SpaceCreateRequestDto dto, CustomUserDetails principal)
             .spaceId(savedSpace.getSpaceId())
             .userId(principal.getUserId())
                 .authority(Authority.ADMIN)
-                .isDeleted(false)
             .build();
 
     SpaceMember spaceMember = spaceMemberMapper.toEntity(adminUser);
diff --git a/src/main/java/org/fastcampus/jober/user/service/UserService.java b/src/main/java/org/fastcampus/jober/user/service/UserService.java
index aa5c25d..c33a01e 100644
--- a/src/main/java/org/fastcampus/jober/user/service/UserService.java
+++ b/src/main/java/org/fastcampus/jober/user/service/UserService.java
@@ -38,6 +38,11 @@ public Long getUserId(String username) throws UsernameNotFoundException {
     return userRepository.findByUsernameAndIsDeletedFalse(username).orElseThrow().getUserId();
   }
 
+  /**
+   * 이메일로 초대받아 진행되는 회원가입
+   * @param req
+   * @param spaceId
+   */
   @Transactional
   public void register(RegisterRequestDto req, Long spaceId) {
     register(req);
@@ -47,9 +52,6 @@ public void register(RegisterRequestDto req, Long spaceId) {
   }
 
 
-  /**
-   * 이메일로 초대받아 진행되는 회원가입
-   */
   @Transactional
   public void register(RegisterRequestDto req) {
     // 입력값 형식 검증
diff --git a/src/main/resources/application-develop.yml b/src/main/resources/application-develop.yml
index f837e91..97601e5 100644
--- a/src/main/resources/application-develop.yml
+++ b/src/main/resources/application-develop.yml
@@ -47,7 +47,6 @@ security:
     - /h2-console/**
     - /admin/sessions/**
   permit-user:
-    - /user/register
     - /user/login
     - /user/id/check
     - /user/email/check
diff --git a/src/main/resources/application-production.yml b/src/main/resources/application-production.yml
index 14abd62..4a23ad8 100644
--- a/src/main/resources/application-production.yml
+++ b/src/main/resources/application-production.yml
@@ -51,7 +51,6 @@ security:
     - /swagger-ui.html
     - /admin/sessions/**
   permit-user:
-    - /user/register
     - /user/login
     - /user/id/check
     - /user/email/check