To provide a fluid pressure rotary apparatus which can suitably aid a vane so as to abut against an inner peripheral surface of a cylinder and has a high degree of compatibility with its fundamental mode.

The fluid pressure rotary apparatus is equipped with a rotor 20 which rotates around a rotating shaft made eccentric relative to the axis of a cylinder 10, a plurality of vanes 30 which are incorporated in a radially movable manner in each rotor groove 22 radially provided in the rotor 20 and contact with an inner peripheral surface 11 of the cylinder, and a fixed cam 50 which is provided, in an inner surface of a side plate 15 for closing both-side surfaces of the cylinder 10, in such a manner as to be coaxial with the axis of the cylinder 10 and to be integral with and fixed to the cylinder 10 so as to contact with a rear end side 30b of the vane 30 and thereby guide the radial-directional movement of the vane, and protrudes by a given length to the inside of the cylinder 10.