One embodiment discloses a pressure buffer device, which includes a pipe-shaped member that stores fluid, and a partitioning member that is movably provided in the pipe-shaped member to partition its space into a first space and a second space. The pressure buffer device further includes a fluid reservoir portion that is arranged at the a radial outer side of the pipe-shaped member to store fluid, and a communication path that is arranged at a radial outer side of the fluid reservoir portion to communicate between the first space and the second space.