diff --git a/gluturtle.cabal b/gluturtle.cabal
--- a/gluturtle.cabal
+++ b/gluturtle.cabal
@@ -2,7 +2,7 @@
 cabal-version:	>= 1.6
 
 name:		gluturtle
-version:	0.0.5
+version:	0.0.6
 stability:	alpha
 author:		Yoshikuni Jujo <PAF01143@nifty.ne.jp>
 maintainer:	Yoshikuni Jujo <PAF01143@nifty.ne.jp>
@@ -28,7 +28,7 @@
   Ghc-options:		-Wall
   Other-modules:	Graphics.UI.GLUT.Turtle.Field, Graphics.UI.GLUT.Turtle.Input,
     Graphics.UI.GLUT.Turtle.Move, Graphics.UI.GLUT.Turtle.State,
-    Graphics.UI.GLUT.Turtle.Data, Graphics.UI.GLUT.Turtle.Layers
+    Graphics.UI.GLUT.Turtle.Data, Graphics.UI.GLUT.Turtle.Layers,
     Graphics.UI.GLUT.Turtle.Triangles, Graphics.UI.GLUT.Turtle.TriangleTools
 
 executable		testTurtle
diff --git a/src/Graphics/UI/GLUT/Turtle/Field.hs b/src/Graphics/UI/GLUT/Turtle/Field.hs
--- a/src/Graphics/UI/GLUT/Turtle/Field.hs
+++ b/src/Graphics/UI/GLUT/Turtle/Field.hs
@@ -232,12 +232,25 @@
 positionToVertex3 :: Position -> Vertex2 GLfloat
 positionToVertex3 (Center x y) =
 	Vertex2 (fromRational $ toRational x / 300)
-		(fromRational $ toRational y / 300 + 0.2)
+		(fromRational $ toRational y / 300)
 positionToVertex3 _ = error "positionToVertex3: not implemented"
 
 writeString :: Field -> Layer -> String -> Double -> Color -> Position ->
 	String -> IO ()
-writeString _f _ _fname _size _clr _pos _str = return ()
+writeString f _ _fname size clr (Center x_ y_) str =
+	atomicModifyIORef_ (fActions f) (action :)
+	where
+	action = preservingMatrix $ do
+		let	size' = size / 15
+			x = 6.666 * fromRational (toRational $ x_ / size')
+			y = 6.666 * fromRational (toRational $ y_ / size')
+			s = 0.0005 * fromRational (toRational size')
+		G.color $ colorToColor4 clr
+		G.scale (s :: GLfloat) (s :: GLfloat) (s :: GLfloat)
+		G.clearColor $= G.Color4 0 0 0 0
+		G.translate (G.Vector3 x y 0 :: G.Vector3 GLfloat)
+		G.renderString G.Roman str
+writeString _ _ _ _ _ _ _ = error "writeString: not implemented"
 
 drawImage :: Field -> Layer -> FilePath -> Position -> Double -> Double -> IO ()
 drawImage _f _ _fp _pos _w _h = return ()
@@ -295,7 +308,8 @@
 	writeIORef (fString f) ""
 	continue <- ($ str) =<< readIORef (fInputtext f)
 	unless continue G.leaveMainLoop
-keyboardProc f (G.Char '\b') G.Down _ _ = atomicModifyIORef_ (fString f) init
+keyboardProc f (G.Char '\b') G.Down _ _ =
+	atomicModifyIORef_ (fString f) $ \s -> if null s then s else init s
 keyboardProc f (G.Char c) state _ _
 	| state == G.Down = atomicModifyIORef_ (fString f) (++ [c])
 	| otherwise = return ()
diff --git a/tests/testGLUT.hs b/tests/testGLUT.hs
--- a/tests/testGLUT.hs
+++ b/tests/testGLUT.hs
@@ -35,4 +35,5 @@
 processInput _ _ "exit" = return False
 processInput f t "position" = position t >>= outputString f . show >> return True
 processInput _ t "penup" = penup t >> return True
+processInput _ t "message" = write t "KochiGothic" 20 "Hello, world!" >> return True
 processInput _ _ _ = return True