To secure normal operation of a pressure intensifying device in spite of the fluctuation of master cylinder hydraulic pressure caused by intermittent suction of a pump, in a brake device intensifying brake cylinder hydraulic pressure to be higher than master cylinder hydraulic pressure by sucking hydraulic fluid from a master cylinder and discharging to a brake cylinder by the pump, as well as controlling the state of pressure intensifying on the basis of an output signal of a master cylinder hydraulic pressure sensor.

On the basis of the output signal of a master cylinder hydraulic pressure sensor, master cylinder hydraulic pressure is provisionally calculated one after another while the final value PM of master cylinder hydraulic pressure is calculated by smoothing a plurality of calculated provisional values (containing the maximum provisional value PM max and the minimum provisional value PM min), and the state of pressure intensifying is controlled on the basis of the calculated final value PM.