diff --git a/kis_agent/core/constants.py b/kis_agent/core/constants.py
index e43207b..9f921c6 100644
--- a/kis_agent/core/constants.py
+++ b/kis_agent/core/constants.py
@@ -11,12 +11,35 @@
 REAL_BASE_URL = "https://openapi.koreainvestment.com:9443"
 MOCK_BASE_URL = "https://openapivts.koreainvestment.com:29443"
 
+# WebSocket 엔드포인트
+# (KIS 공식 샘플 open-trading-api/legacy/websocket/python/* 에서 확인된 값)
 WS_REAL_URL = "ws://ops.koreainvestment.com:21000"
 WS_MOCK_URL = "ws://ops.koreainvestment.com:31000"
 
 KIS_USER_AGENT_DEFAULT = "KIS_AGENT"
 
 
+def get_ws_url(is_real: bool = True) -> str:
+    """실전/모의 WebSocket URL을 선택한다.
+
+    KIS는 실전과 모의 WS 엔드포인트를 분리 운영한다:
+    - 실전: `ws://ops.koreainvestment.com:21000` (`WS_REAL_URL`)
+    - 모의: `ws://ops.koreainvestment.com:31000` (`WS_MOCK_URL`)
+
+    Args:
+        is_real: True면 실전 URL, False면 모의 URL.
+
+    Returns:
+        선택된 WebSocket URL.
+
+    Example:
+        >>> from kis_agent.core.constants import get_ws_url
+        >>> from kis_agent.websocket import WSAgent
+        >>> ws = WSAgent(approval_key, url=get_ws_url(is_real=False))
+    """
+    return WS_REAL_URL if is_real else WS_MOCK_URL
+
+
 class AccountProductCode(str, Enum):
     """계좌 상품코드 (KIS 공식).
 
@@ -35,4 +58,5 @@ class AccountProductCode(str, Enum):
     "WS_MOCK_URL",
     "KIS_USER_AGENT_DEFAULT",
     "AccountProductCode",
+    "get_ws_url",
 ]
diff --git a/kis_agent/websocket/__init__.py b/kis_agent/websocket/__init__.py
index ff3a334..c5f0d23 100644
--- a/kis_agent/websocket/__init__.py
+++ b/kis_agent/websocket/__init__.py
@@ -17,6 +17,10 @@
     ws.subscribe_stocks(["005930", "000660"])
     await ws.connect()
 
+    # 모의투자 엔드포인트 사용
+    from kis_agent.core.constants import get_ws_url
+    ws = WSAgent(approval_key, url=get_ws_url(is_real=False))
+
 .. deprecated:: 1.3.0
     KisWebSocket, EnhancedWebSocketClient, RefactoredWebSocketClient,
     WebSocketClientFactory, WebSocketClientBuilder는 deprecated되었습니다.