To enhance the operational feeling in stamping a pedal by reducing the influence of a hysteresis on the output pressure for the pedal stamping angle.

The operating force given by a brake pedal 3 is transmitted to a piston 10 through a plunger 7, a spring receptacle 8, and operating force transmission springs 9a, 9b, wherein the spring receptacle 8 can move up and down under guidance of the guide rod 10a of the piston 10, and the exhaust path 17c is shut off from the output port 12b by a supply/exhaust valve body 17 while the supply port 12a is put in communication with the output port 12b. A ring-shaped sliding member 36 to fit slidably on the guide rod 10a receives the operating force through the spring receptacle 8, and in the forward stroke, transmits the operating force to the guide rod 10a through utilization of the slide resistance based upon the friction. In the return stroke, the reaction force directed oppositely to the operating force is transmitted to the guide rod 10a through the sliding resistance.