In accordance with operation, data on a starting point, a destination, and
a display scale are inputted to set a first route from the starting point
to the destination based on the inputted data on the starting point and
the destination. In case an obstacle which blocks a smooth traveling of
the vehicle is detected in the first route, a second route to bypass the
obstacle is searched for. In accordance with the inputted display scale,
the range of display of the map information to be displayed is set. With
the traveling of the vehicle, the map information to be displayed in the
range of display is successively updated. In case the searched for second
route is to be displayed, the new range of display is set irrespective of
the inputted display scale so that the overall second route is displayed
simultaneously with the first route.
