diff --git a/src/test/java/camp/woowak/lab/web/resolver/session/SessionVendorArgumentResolverTest.java b/src/test/java/camp/woowak/lab/web/resolver/session/SessionVendorArgumentResolverTest.java
new file mode 100644
index 00000000..36e7db30
--- /dev/null
+++ b/src/test/java/camp/woowak/lab/web/resolver/session/SessionVendorArgumentResolverTest.java
@@ -0,0 +1,135 @@
+package camp.woowak.lab.web.resolver.session;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.lang.annotation.Annotation;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.core.MethodParameter;
+import org.springframework.web.context.request.NativeWebRequest;
+
+import camp.woowak.lab.common.exception.UnauthorizedRequestException;
+import camp.woowak.lab.web.authentication.LoginCustomer;
+import camp.woowak.lab.web.authentication.LoginVendor;
+import camp.woowak.lab.web.authentication.annotation.AuthenticationPrincipal;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpSession;
+
+@ExtendWith(MockitoExtension.class)
+class SessionVendorArgumentResolverTest {
+	@InjectMocks
+	private SessionVendorArgumentResolver resolver;
+	@Mock
+	private MethodParameter methodParameter;
+	@Mock
+	private NativeWebRequest webRequest;
+	@Mock
+	private HttpServletRequest request;
+	@Mock
+	private HttpSession session;
+	@Mock
+	private LoginVendor mockVendor;
+
+	@Nested
+	@DisplayName("supportsParameter")
+	class SupportsParameter {
+		@Test
+		@DisplayName("[True] 파라미터에 @AuthenticationPrincipal이 붙은 경우")
+		public void supportsParameter_ReturnsTrue_WhenCorrectAnnotationAndType() {
+			when(methodParameter.hasParameterAnnotation(AuthenticationPrincipal.class)).thenReturn(true);
+			when(methodParameter.getParameterType()).thenReturn((Class)LoginVendor.class);
+
+			boolean supports = resolver.supportsParameter(methodParameter);
+
+			assertThat(supports).isTrue();
+		}
+
+		@Test
+		@DisplayName("[False] 파라미터가 LoginVendor가 아닌 경우")
+		public void supportsParameter_ReturnsTrue_WhenIncorrectType() {
+			when(methodParameter.hasParameterAnnotation(AuthenticationPrincipal.class)).thenReturn(true);
+			when(methodParameter.getParameterType()).thenReturn((Class)LoginCustomer.class);
+
+			boolean supports = resolver.supportsParameter(methodParameter);
+
+			assertThat(supports).isFalse();
+		}
+
+		@Test
+		@DisplayName("[False] 파라미터에 @AuthenticationPrincipal이 붙지 않은 경우")
+		public void supportsParameter_ReturnsFalse_WhenIncorrectAnnotationOrType() {
+			when(methodParameter.hasParameterAnnotation(AuthenticationPrincipal.class)).thenReturn(false);
+
+			boolean supports = resolver.supportsParameter(methodParameter);
+
+			assertThat(supports).isFalse();
+		}
+	}
+
+	@Nested
+	@DisplayName("resolveArgument")
+	class ResolveArgument {
+		@Test
+		@DisplayName("[LoginVendor] 세션에 LoginVendor 있는 경우")
+		public void resolveArgument_ReturnsVendor_WhenSessionExists() throws Exception {
+			when(webRequest.getNativeRequest()).thenReturn(request);
+			when(request.getSession(false)).thenReturn(session);
+			when(session.getAttribute(SessionConst.SESSION_VENDOR_KEY)).thenReturn(mockVendor);
+			when(methodParameter.getParameterAnnotation(AuthenticationPrincipal.class)).thenReturn(
+				new AuthenticationPrincipal() {
+					@Override
+					public Class<? extends Annotation> annotationType() {
+						return null;
+					}
+
+					@Override
+					public boolean required() {
+						return true;
+					}
+				}
+			);
+
+			Object result = resolver.resolveArgument(methodParameter, null, webRequest, null);
+
+			assertThat(result).isEqualTo(mockVendor);
+		}
+
+		@Test
+		@DisplayName("[Null] 파라미터에 @AuthenticationPrincipal이 붙지 않은 경우")
+		public void resolveArgument_ReturnsNull_WhenSessionDoesNotExist() throws Exception {
+			Object result = resolver.resolveArgument(methodParameter, null, webRequest, null);
+
+			assertThat(result).isNull();
+		}
+
+		@Test
+		@DisplayName("[UnauthorizedRequestException] @AuthenticationPrincipal(required=true)인데 세션이 LoginVendor가 없는 경우")
+		public void resolveArgument_ThrowsException_WhenSessionRequiredButMissing() {
+			when(webRequest.getNativeRequest()).thenReturn(request);
+			when(methodParameter.getParameterAnnotation(AuthenticationPrincipal.class)).thenReturn(
+				new AuthenticationPrincipal() {
+					@Override
+					public boolean required() {
+						return true;
+					}
+
+					@Override
+					public Class<? extends Annotation> annotationType() {
+						return AuthenticationPrincipal.class;
+					}
+				});
+
+			assertThrows(
+				UnauthorizedRequestException.class,
+				() -> resolver.resolveArgument(methodParameter, null, webRequest, null));
+		}
+	}
+}