Patent ID: 7926268

Claim:
A master cylinder comprising: a cylinder body arranged in communication with a reservoir; a reservoir connection port formed at a surface of the cylinder body and being in communication with the reservoir; a pressure chamber formed inside of the cylinder body; a reservoir fluid passage connecting the reservoir connection port and the pressure chamber to each other; a valve mechanism accommodated within the reservoir connection port and reducing an amount of fluid flowing in the reservoir fluid passage in a case where the reservoir fluid passage is at a high pressure; a valve body including a small diameter cylindrical portion and a large diameter cylindrical portion, the small diameter cylindrical portion forming a passage by means of which the reservoir and the reservoir fluid passage communicate with each other, the large diameter cylindrical portion having one end connected to an end portion of the small diameter cylindrical portion and the other end fixed to the reservoir connection port, the valve body accommodating the valve mechanism; and a first seal member sealing between an outer periphery of the small diameter cylindrical portion and the reservoir and a second seal member sealing between an outer periphery of the large diameter cylindrical portion and the reservoir connection port.