Cup seals are fitted to a cylinder hole of a hydraulic pressure master cylinder. A plunger is movably inserted into the cylinder hole via the cup seals. A fluid chamber is formed on an outer circumferential side of the cylinder hole and between the cup seals so as to communicate with a fluid storage chamber through a fluid communication hole. The plunger is formed in a cylindrical shape having a bottom and provided with a recess portion opening toward a bottom portion of the cylinder hole. A hydraulic pressure chamber is defined between the recess portion and the bottom portion. Plural communication ports are formed in a circumferential wall of the recess portion, to penetrate the circumferential wall. When the plunger is in an initial position and is in a non-operating state, the communication ports connect the hydraulic pressure chamber and the fluid chamber.