To reduce a manufacturing cost by providing a frictional element controlling part which duty-controls line pressure or the like and selectively supplies it to the fricitonal elements, selectively supplying the controlled hydraulic pressure to the frictional elements through switch valves, thereby reducing number of valves and simply composing a hydraulic pressure circuit.

A manual valve 12 is interlocked with a shift lever for transmitting liquid pressure output from a pressure governing valve 6 which converts a pump discharge pressure to a constant value to respective frictional elements. A frictional element controlling part A is composed of solenoid valves S1 to S6 for duty-controlling a line pressure and a drive pressure and selectively supplying them to the frictional elements. Hydraulic pressure controlled by the frictional element controlling part A is selectively supplied to the fricitonal elements through switch valves 100, 102 and 106. The pressure governing valve 6 is connected to a clutch regulator valve 8 which supplies the hydraulic pressure to a torque converter, through a pipe passage on which a converter field valve 10 is arranged.