1. A navigation system for providing road guidance by displaying a structure-shape map showing shapes of buildings, facilities, and roads, said navigation system comprising: present-position sensing means for sensing a present position; vehicle speed sensing means for sensing vehicle speed; storage means containing stored structure-shape map data including shape information representing shapes of structures, said structures including at least roads, facilities and buildings, and information regarding said structures linked to said shape information; display means for displaying the structure-shape map with the sensed present position indicated thereon, based on the shape information; and display control means for, in one mode of operation, controlling information displayed as said structure-shape map on said display means in accordance with movement of the sensed present position, restricting the quantity of shape information which is displayed on said display means to shape information for structures within a predefined area around the present position, on the basis of the sensed vehicle speed, for selecting items of said information regarding said roads from said storage means on the basis of the sensed present position, and for drawing, within an area smaller than the displayed structure-shape map, only the selected items of said information regarding said roads overlaid on the respectively related shapes of roads on the displayed structure-shape map.