PURPOSE: To provide a brake device for a vehicle which can attain small size of the device, decrease the manufacturing cost, and improve loading adaptability on a vehicle.

CONSTITUTION: This brake device is constituted of a master cylinder unit 4 in which a master cylinder 12 is connected to a brake booster 13, a unit which is provided separately from the brake booster 13 and master cylinder 12, and can discriminately distribute the brake pressure generated in the master cylinder by operation of a brake pedal 14 to right and left disc brake mechanisms 60, and a braking force distribution control unit 8 (containing a braking force distribution control circuit 10) which can supply different brake pressure to the right and left disc brake mechanisms 60, independently of operation of the brake pedal 14.