PURPOSE: To simplify the keying operation by reading and displaying the map of an arbitrary place and the map of the driver's own vehicle from a recording medium, and reading and displaying more detailed map as the vehicle approaches an input destination.

CONSTITUTION: A controller 1 displays a driver's own vehicle position from his own vehicle position processor 6, map data from a recording medium reader 3 and a destination from a key input unit 2 on a display unit 5b. When an auto-mode is selected by the unit 2, the controller 1 retrieves a map data base 4 in which a present position and the destination coexist by the reader 3, confirms whether there is more detailed map or not, select and reads, if there is, it, and displays it on the unit 5b. Then, the driver's own vehicle position is displayed on the map. Further, the controller confirms whether his own position arrives at the destination or not, again sets the auto-mode, if it does not arrive at the destination, repeats the same process, and completes, if it arrives, the process. Thus, necessary map can be automatically read without necessity of a complicated operation.