diff --git a/src/main/java/org/swmaestro/repl/gifthub/auth/service/OAuthService.java b/src/main/java/org/swmaestro/repl/gifthub/auth/service/OAuthService.java
index 0c739309..76b8087d 100644
--- a/src/main/java/org/swmaestro/repl/gifthub/auth/service/OAuthService.java
+++ b/src/main/java/org/swmaestro/repl/gifthub/auth/service/OAuthService.java
@@ -92,7 +92,7 @@ public OAuthUserInfoDto mapToDto(OAuth oAuth) {
 				.id(oAuth.getPlatformId())
 				.email(oAuth.getEmail())
 				.nickname(oAuth.getNickname())
-				.Provider(oAuth.getPlatform().toString())
+				.Provider(oAuth.getPlatform().toString().toLowerCase())
 				.build();
 	}
 }
diff --git a/src/main/java/org/swmaestro/repl/gifthub/auth/service/UserService.java b/src/main/java/org/swmaestro/repl/gifthub/auth/service/UserService.java
index 18a30dbf..8588d546 100644
--- a/src/main/java/org/swmaestro/repl/gifthub/auth/service/UserService.java
+++ b/src/main/java/org/swmaestro/repl/gifthub/auth/service/UserService.java
@@ -74,14 +74,14 @@ public boolean isValidatePassword(String password) {
 	public User read(String username) {
 		User user = userRepository.findByUsername(username);
 		if (user == null) {
-			return null;
+			throw new BusinessException("존재하지 않는 회원입니다.", StatusEnum.NOT_FOUND);
 		}
 		return user;
 	}
 
 	public UserReadResponseDto read(Long id) {
 		Optional<User> user = userRepository.findById(id);
-		if (user.isEmpty() || user.get().getDeletedAt() != null) {
+		if (user.isEmpty() || !user.get().isEnabled()) {
 			throw new BusinessException("존재하지 않는 회원입니다.", StatusEnum.NOT_FOUND);
 		}
 		return UserReadResponseDto.builder()
diff --git a/src/main/java/org/swmaestro/repl/gifthub/filter/JwtAuthenticationFilter.java b/src/main/java/org/swmaestro/repl/gifthub/filter/JwtAuthenticationFilter.java
index c3955f59..8d9d7d81 100644
--- a/src/main/java/org/swmaestro/repl/gifthub/filter/JwtAuthenticationFilter.java
+++ b/src/main/java/org/swmaestro/repl/gifthub/filter/JwtAuthenticationFilter.java
@@ -1,33 +1,54 @@
 package org.swmaestro.repl.gifthub.filter;
 
-import jakarta.servlet.FilterChain;
-import jakarta.servlet.ServletException;
-import jakarta.servlet.http.HttpServletRequest;
-import jakarta.servlet.http.HttpServletResponse;
-import lombok.RequiredArgsConstructor;
+import java.io.IOException;
+
 import org.springframework.core.annotation.Order;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
 import org.springframework.stereotype.Component;
 import org.springframework.web.filter.OncePerRequestFilter;
+import org.swmaestro.repl.gifthub.util.ErrorMessage;
 import org.swmaestro.repl.gifthub.util.JwtProvider;
+import org.swmaestro.repl.gifthub.util.StatusEnum;
 
-import java.io.IOException;
+import com.fasterxml.jackson.databind.ObjectMapper;
 
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import lombok.RequiredArgsConstructor;
 
 @Order(0)
 @Component
 @RequiredArgsConstructor
 public class JwtAuthenticationFilter extends OncePerRequestFilter {
 	private final JwtProvider jwtProvider;
+	private final ObjectMapper objectMapper = new ObjectMapper();
 
 	@Override
-	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
+	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException,
+			UsernameNotFoundException {
 		String token = jwtProvider.resolveToken(request);
 		if (token != null && jwtProvider.validateToken(token)) {
 			token = token.substring(7);
-			Authentication auth = jwtProvider.getAuthentication(token);
-			SecurityContextHolder.getContext().setAuthentication(auth);
+			try {
+				Authentication auth = jwtProvider.getAuthentication(token);
+				SecurityContextHolder.getContext().setAuthentication(auth);
+			} catch (UsernameNotFoundException e) {
+				e.printStackTrace();
+				response.setStatus(401);
+				response.setCharacterEncoding("utf-8");
+				response.setContentType("application/json");
+				response.getWriter().write(objectMapper.writeValueAsString(
+						ErrorMessage.builder()
+								.status(StatusEnum.UNAUTHORIZED.statusCode)
+								.path(request.getRequestURI())
+								.error("탈퇴한 회원입니다.")
+								.build()));
+				return;
+			}
 		}
 		filterChain.doFilter(request, response);
 	}
diff --git a/src/main/java/org/swmaestro/repl/gifthub/util/JwtProvider.java b/src/main/java/org/swmaestro/repl/gifthub/util/JwtProvider.java
index 087b003a..cc790c09 100644
--- a/src/main/java/org/swmaestro/repl/gifthub/util/JwtProvider.java
+++ b/src/main/java/org/swmaestro/repl/gifthub/util/JwtProvider.java
@@ -10,6 +10,7 @@
 import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
 import org.springframework.stereotype.Component;
 import org.swmaestro.repl.gifthub.auth.repository.RefreshTokenRepository;
 import org.swmaestro.repl.gifthub.auth.service.UserService;
@@ -96,6 +97,9 @@ public String resolveToken(HttpServletRequest request) {
 	 */
 	public Authentication getAuthentication(String token) {
 		UserDetails userDetails = userService.loadUserByUsername(this.getUsername(token));
+		if (userDetails == null) {
+			throw new UsernameNotFoundException("존재하지 않는 회원입니다.");
+		}
 		return new UsernamePasswordAuthenticationToken(userDetails, "", userDetails.getAuthorities());
 	}