Abstract: An automatic transmission comprises a metal V-belt mechanism 10, which changes the speed ratio of the rotational output from an engine ENG, a forward/reverse direction change mechanism 20, which switches the rotational direction of the ratio-change mechanism, and a forward clutch 30, which actuates the switching operation of the rotational direction performed by the forward/reverse direction-change mechanism. A control system for this transmission comprises a regulator valve 50, which generates a line pressure, a manual valve 80, which is operated in correspondence to the shift lever and switches the supply of the line pressure to the forward clutch, and a drive-range sensor 105, which detects the operation of the manual valve. When the movement of the manual valve to a position where the line pressure is to be supplied to the forward clutch is detected by the drive-range sensor 105, the line pressure, which is adjusted by the regulator valve, is lowered for a predetermined time period.