PURPOSE: To disable achievement of reverse stage even if an operating state switching valve is switched to reverse position during drive operation by providing an oil path switching mechanism for discharging hydraulic pressure to be fed to a reverse friction element when the engine rotation is higher than a predetermined level and the operating state switching valve is switched to first position.

CONSTITUTION: Upon erroneous switching of an operating state switching valve 1 to reverse position when the vehicle speed exceeds over a predetermined level, hydraulic pressure P1 flows between the lands 8, 9 in the switching valve 1 into oil paths 2, 3. A vehicle speed sensor 20 detects vehicle speed exceeding over a predetermined level, then a controller 18 controls a solenoid valve 17 based on an output from the sensor 20 to release pressure oil from an oil path 16 so as to slide a spool valve 11 to the left and bring to a hydraulic pressure discharging position. Consequently, pressure oil fed through the oil path 3 between lands 12, 13 of an oil path switching valve 10 is discharged through an oil discharge path 16 and not fed to a low reverse brake 5. Since reverse stage is not achieved even upon switching of the switching valve 1 to reverse position, abrupt braking or engine stall does not occur.