Disclosed is a monitor device for a moving body such as a vehicle, aircraft or vessel, moving at a certain speed. The monitor device displays an image of a front scene of the moving body with the image of the central area being enlarged in accordance with the running speed of the moving body such that condition of a far away portion can be recognized accurately. A zoom ratio calculating section determines a zoom ratio in accordance with running speed of the moving body. The area of image to be displayed is selected in accordance with the zoom ratio and the image of the selected area is displayed on a display screen in an enlarged form. A specially designed distortion lens may be used to take the picture of the front scene to form an image of the scene with its central area being optically enlarged.