A control system for an automatic vehicle transmission having an auto-shifting device for determining an auto-shifting gearshift signal indicative of a gear to be shifted to in accordance with predetermined gearshift scheduling characteristics in response to a detected vehicle speed and an engine load, and a manual-shifting device for determining a manual-shifting signal indicative of a gear to be shifted to in response to a manual-shift command. A gearshift is conducted in response to one of the auto-shifting gearshift signal and the manual-shifting gearshift signal. In the system, the manual-shifting command is inhibited from being accepted for a predetermined period since the gearshift device conducted a gearshift in response to the auto-shifting gearshift signal. With this arrangement, it is possible to prevent down shifting from occurring consecutively so as to prevent drivability or driver's comfort from being degraded.