PURPOSE: To keep antilock control, traction slip control and the merit of a brake distributor by controlling a valve system and operationally connecting the pump of a combination device so as to form the brake pressure of front wheels when the over control tendency of a hydraulic brake system exceeds a permissible limit.

CONSTITUTION: Respective signals from sensors 51a-51d, brake lamp switch 3 and pressure sensors 48 and 49 arranged on respectively correspondent wheels are inputted to a control unit 50. The monitoring device 50 monitors the over control tendency from these respective kinds of inputted information at all the time. When the over control tendency reaches the permissible limit, a brake circuit switching valve, traction slip control, inlet valve and outlet valve, which are connected by a connection conduit pipe 52, or the like are controlled. Besides, pumps such as front load pump and return feed pump, for example, connected by a conduit pipe 53 are controlled.