PURPOSE: To improve the cornering performance of a car by sensing the difference of rotation between the left and right driving wheels of the car during drive at a corner on a gravel road and obtaining the middle value of oil pressure for the purpose of application of half-braking to the wheel rotating at higher speed through changing the duty of the ON/OFF control signal.

CONSTITUTION: Signals from sensors 10, 20 provided at the right and left driving wheels are put into a subtraction circuit 100, which produces an output in accordance with the difference of their rotation and gives it to a comparator 120. This comparator 120 compares it with the reference value and gives an output to a logic product circuit 150 when the difference between the given signal and the reference value exceeds a certain level. Another input to the logic product circuit 150 is fed by a duty control device 140, which is to control the signal of an oscillator 50 with the rotation difference signal from the subtraction circuit 100, whereby the output from the logic product circuit 150 is duty-controlled in accordance with the difference of rotation between the left and right driving wheels. At this time, actuators 190, 200 control the braking oil pressure in accordance with the duty ratio. This control can be performed smoothly, as any oil pressure is available if lower than the supplied oil pressure.