The view point-setting part calculates the position of the view point V to be set behind the current position of the car and up in the air, based on the current position calculated by the current position-measuring part and the position correcting part. The data reading part reads out map data M about map elements such as buildings, which are located around the current position. The representing method-changing part calculates the distance or level difference between the viewpoint and each of the map elements, and, for example, changes the representation shapes of ones of the map elements near the view point, that is, in the region within a predetermined distance from the view point, to detailed shapes, and the rest ones far from the view point, that is, outside the region within a predetermined distance from the view point, to simple shapes, respectively. Finally, the display processing part composes an image of each of the map element according to the displaying mode of the map element, which is sent from the representation method-changing part, and displays the image.