To save power by reducing a supply current to an electric booster brake device since the hydraulic pressure of a master cylinder does not need to directly respond to a brake operating force during antiskid control.

If a current I adaptive to a brake depressing force F is supplied, as shown by broken lines, to a booster motor during the antiskid control (depressurized) (t3 to t5) for preventing wheel lock, the hydraulic pressure Pm of the master cylinder is unnecessarily high as shown by the broken line though the brake hydraulic pressure is being reduced during the antiskid control, and the power consumption of the booster motor is increased accordingly. To reduce, during that period, the hydraulic pressure Pm of the master cylinder from the hydraulic pressure P0 at the start of the antiskid control (depressurized) as shown by the solid lines to Po' or P7 max. within the range in which a vehicle deceleration and the brake depressing force are not changed, the current I to the booster motor is lowered from I0 adaptive to P0 to i' or I', thereby enabling the assisting force of the electric booster brake device to be lowered.