PURPOSE: To prevent the stability of a vehicle from lowering when a booster valve cable breakage, etc., occurs by providing an acceleration slip brake control stop means to stop an acceleration slip brake control, when a drive wheel acceleration and deceleration detecting means detects a drive wheel deceleration over a specified limit during the acceleration slip brake control.

CONSTITUTION: When a detection value from an acceleration slip condition detector means (e) comes over a specified limit, an acceleration slip brake control means (g) outputs a control instruction to a brake fluid pressure control actuator (d). By this control, a drive wheel slip is suppressed according to a brake fluid pressure from an external fluid pressure source (b) to a wheel cylinder (c) of a drive wheel. In this case, if a booster valve (a) is kept at a boosting position due to cable breakage of the booster valve or cable breakage of a drive circuit to decelerate the drive wheel and a deceleration over a specified limit is detected by a drive wheel acceleration and deceleration detector means (f), an acceleration slip brake control stop means (h) will stop an acceleration slip brake control.