PURPOSE: To prevent hunting at a time of such as climbing a slope by prohibiting up-shift to higher speed gear for a fixed time thereafter when down- shift occurs under a throttle opening over what set for the vehicle speed during constant speed running on cruise control.

CONSTITUTION: Automatic drive control is performed through that a vehicle speed sensor 5 and respective switches 6, 7 of an automatic drive, control and cancel switch, are input to an automatic drive computer 1 and control signal is output to a throttle valve opening and closing actuator 8 in opening and closing adjustment and to an automatic transmission in an electronic control unit 10. When down shift occurs at a throttle opening over wheat set in corre sponding to the vehicle speed during constant speed running on cruise control, up-shift to higher speed gear is prohibited during a fixed time thereafter. It is made possible to avoid hunting phenomenon repeating up-shift and down-shift on such as climbing a slope and to run comfortably.