PURPOSE: To avoid 'shift up' at the time of an accelerator having been closed suddenly, conducting gear position decision on the basis of a predetermined substitutive accelerator opening for a predetermined period after it is detected that an accelerator opening change speed in a closing direction is more than a predetermined level.

CONSTITUTION: During vehicle operation, the respective detecting signals of a vehicle speed sensor 5 and a throttle sensor 4 are inputted at an automatic shift control unit 6 with a microcomputer built inside, and by this unit 6, a gear position is decided on the basis of a vehicle speed, a throttle opening and in addition the information of a brake switch 8 that becomes ON at the time of braking by means of a brake, and the opening duty of each solenoid valve 7A-7E is controlled. In this instance, arrangement is made so that gear position decision may be conducted on the basis of, instead of an actual throttle opening, a predetermined substitutive opening that is more on the side of opening in contrast to the actual opening, for a predetermined period after it is detected that an accelerator opening, that is, a throttle opening change speed in a closing direction is more than a predetermined level.