diff --git a/gremlin-haskell.cabal b/gremlin-haskell.cabal
--- a/gremlin-haskell.cabal
+++ b/gremlin-haskell.cabal
@@ -1,5 +1,5 @@
 name:                gremlin-haskell
-version:             0.1.0.1
+version:             0.1.0.2
 synopsis:            Graph database client for TinkerPop3 Gremlin Server
 description:         Please see README.md
 homepage:            http://github.com/nakaji-dayo/gremlin-haskell
@@ -36,6 +36,7 @@
                      , mtl
                      , stm
                      , uuid
+                     , transformers
   default-language:    Haskell2010
  
 executable gremlin-haskell-examples
diff --git a/src/Database/TinkerPop.hs b/src/Database/TinkerPop.hs
--- a/src/Database/TinkerPop.hs
+++ b/src/Database/TinkerPop.hs
@@ -11,8 +11,9 @@
 import Database.TinkerPop.Types
 import Database.TinkerPop.Internal
 
-import Prelude hiding (putStrLn)
+import Prelude
 import qualified Network.WebSockets as WS
+import Control.Exception
 
 import qualified Data.Map.Strict as M
 import Data.Text (unpack)
@@ -20,19 +21,22 @@
 import qualified Control.Monad.STM as S
 import qualified Control.Concurrent.STM.TChan as S
 import qualified Control.Concurrent.STM.TVar as S
+import qualified Control.Concurrent.MVar as MV
 import qualified Data.UUID as U
 import qualified Data.UUID.V4 as U
 import Control.Lens
 
 -- | Connect to Gremlin Server
 run :: String -> Int -> (Connection -> IO ()) -> IO ()
-run host port app = do    
-    WS.runClient host port "/" $ \ws -> do
+run host port app = do
+    handle (wsExceptionHandler "main thread") $ WS.runClient host port "/" $ \ws -> do
+        done <- MV.newEmptyMVar
         cs <- S.newTVarIO M.empty
         let conn = Connection ws cs
-        _ <- handle conn
+        _ <- handler conn done
         app conn
         close conn
+        MV.takeMVar done
 
 -- | Send script toGremlin Server and get the result by List
 --
diff --git a/src/Database/TinkerPop/Internal.hs b/src/Database/TinkerPop/Internal.hs
--- a/src/Database/TinkerPop/Internal.hs
+++ b/src/Database/TinkerPop/Internal.hs
@@ -5,12 +5,13 @@
 import Data.Text (Text, pack, append)
 import Data.Text.IO
 import Data.Text.Encoding
+import Control.Exception
 import qualified Data.Map.Strict as M
 import qualified Control.Monad.STM as S
 import qualified Control.Concurrent.STM.TChan as S
 import qualified Control.Concurrent.STM.TVar as S
 import Control.Concurrent
-import Control.Monad (forever)
+import Control.Monad
 import Control.Lens
 import Data.Aeson (eitherDecodeStrict)
 import qualified Network.WebSockets as WS
@@ -20,18 +21,31 @@
 inStatus2xx x =  (x `quot` 100) == 2
 
 -- | Start thread to recieve response
-handle :: Connection -> IO (ThreadId)
-handle conn = do
-    forkIO $ forever $ do
-        msg <- WS.receiveData (conn ^. socket) :: IO Text
---        putStrLn $ "recv: " `append` msg
-        case eitherDecodeStrict (encodeUtf8 msg) of
-         Right r -> do
-             cs <- S.readTVarIO (conn ^. chans)
-             case M.lookup (r ^. requestId) cs of
-              Just chan -> S.atomically $ S.writeTChan chan (Right r)
-              Nothing -> putStrLn $ "ERROR: chan not found"
-         Left s -> putStrLn $ "ERROR: parse response message: " `append` (pack s)
+handler :: Connection -> MVar () -> IO ()
+handler conn done = do
+    void $ forkIO $ do
+        handle (wsExceptionHandler "child thread") $ forever $ do
+            msg <- (WS.receiveData (conn ^. socket) :: IO Text)
+            case eitherDecodeStrict (encodeUtf8 msg) of
+             Right r -> do
+                 cs <- S.readTVarIO (conn ^. chans)
+                 case M.lookup (r ^. requestId) cs of
+                  Just chan -> S.atomically $ S.writeTChan chan (Right r)
+                  Nothing -> putStrLn $ "ERROR: chan not found"
+             Left s -> putStrLn $ "ERROR: parse response message: " `append` (pack s)
+        putMVar done ()
+
+-- | Handle exception from websocket.
+--
+-- Ignore ConnectionClised exception that expected.
+wsExceptionHandler :: Text -> SomeException -> IO ()
+wsExceptionHandler label e = do
+    -- putStrLn $ "handle exception[" `append` label `append` "]: " `append` (pack $ show e)
+    case fromException e of
+     Just WS.ConnectionClosed -> return ()
+     _ -> do
+         putStrLn $ "unexpect exception[" `append` label `append` "]: " `append` (pack $ show e)
+         throw e
 
 -- | Close connection
 close :: Connection -> IO ()