To reduce the torque loss of an oil pump by providing a setting means for forcibly opening an orifice communicated with a regulator valve and setting line pressure to zero during two-wheel driving.

Each discharge pressure of first and second oil pumps 23 and 26 is supplied from oil passages 28 and 29 through one-way valves 30 and 31 to a regulator valve 32 and a shift valve 33. The regulator valve 32 adjusts each discharge pressure to line pressure, and the shift valve 33 switches the line pressure. During 2WD traveling, a solenoid valve 35 is switched OFF and an orifice 43 communicated with the regulator valve 32 is opened. Thus, the regulator valve 32 is moved against a spring 39 in a lower direction shown in the drawing to fully open an oil passage 40. Accordingly, the line pressure becomes zero and torque losses by the oil pumps 23 and 26 are reduced.