In step ST11 of FIG. 5, a map image is displayed. In step ST12, moving-route marks are added to the map image. In step ST13, image-pickup-position marks are added to the map image. In step ST14, a current position mark is added to the map image. In step ST15, a predetermined range is determined based on an image-pickup position. Furthermore, predetermined ranges are determined based on a moving route and a current position. In step ST16, the number of types of landmark sign to be included in the map image is reduced in ranges other than the predetermined ranges. Since landmark signs which are positioned far from the image-pickup position, the moving route, and the current position and which are not important for a user are not added to the map image, map display is performed while display of the landmark signs is optimized.