PURPOSE: To constitute a simplified brake hydraulic pressure controller which does not require a hydraulic pressure detector by providing a hydraulic pressure control circuit generating decompression signal in proportion to the output signal from a carrying load sensor and a hydraulic pressure control valve changing the value of break point brake hydraulic pressure which starts decompression and keeping the pressure reducing signal to a preset value by function of these devices during working of brake.

CONSTITUTION: A hydraulic pressure is applied to two front brakes which is one of two systems from a master cylinder 12 and to a brake cylinder 30 fitted to each of two rear brakes from the master cylinder 12 through a hydraulic pressure control valve 20 as another system. And a hydraulic pressure control circuit 40 controls the hydraulic pressure control valve 20 with signals from a vehicle height sensor 13 and a brake switch 14, that is, when a signal from the vehicle height sensor 13 is supplied to the said circuit 40 through a key switch 15 in on-condition and, moreover, brake stepping is confirmed with the brake switch 14, the said circuit 40 supplies the electric current in response to the carrying load detecting signal to the hydraulic pressure control valve 20 and controls the hydraulic pressure applied to rear brakes 30. And the electric current supplied to the hydraulic pressure control valve 20 is kept to a steady value as long as the brake is in working condition.