To solve problems where attention is required at assembling and designing is difficult in a piston pump motor when a cylinder bore and a kidney port are arranged in an unequal pitch in order to reduce the noise.

This piston pump motor is provided with a cylinder block 3 having a plurality of the cylinder bores 4 for suctioning and delivering the fluid from a valve plate 11 having a suction port and a delivery port of the fluid, and a swash plate 7 for suctioning and delivering the fluid from the valve plate 11 to the cylinder bore 4 by reciprocating a plurality of pistons 5 and 6 suctioning and delivering the fluid into a plurality of the cylinder bores 4. A plurality of the pistons 5 and 6 are constituted by mixing the solid piston 5 and the hollow piston 6 exhibiting different damper functions depending on a fluid pressure actuating from the valve plate 11 side. Thus, a tone color is varied so that the high sound is reduced from the operation sound.