When a present position is determined to be included in a high upland area, it is determined whether a presently displayed image can be displayed continuously during the stop of a hard disk drive. For example, a map image may be presently displayed based on map data stored in the hard disk drive. In such a case, displaying the map image cannot be continued in the state of the hard disk drive disabled at the high upland area. Thus, a subsequently displayed image is selected either from an image based on design image data stored in an external memory or from a video obtained from an external video apparatus. The display is changed to the selected image or video.