PURPOSE: To avoid danger when approaching a crowded region and also to keep passengers from feeling something wrong.

CONSTITUTION: An antenna 14 is provided for receiving information about the position of a vehicle from a satellite S and information about traffic jams from a traffic station T and a ROM pack 15 is provided in which map information is stored. A navigation ECU 1 overlaps the position of the vehicle on a crowded region on a map so as to determine whether the crowded region is in a nearby area. When the crowded region is in the nearby area an engine ECU 2 gradually decreases the opening ceiling value of a throttle valve from a normal value toward a reduced value suited for crowded regions. Thus when a crowded region is in a nearby area danger caused by overtaking a decelerated vehicle ahead by means of excessive acceleration is not felt, and since the opening ceiling value is varied slowly, passengers do not feel something wrong.