To provide a piston for a fluid machinery which reduces the sliding resistance with a housing side of the fluid machinery and reduces the cost.

The piston 20 comprises a metal connection part 41 and a resin piston body 40 bonded thereto. The piston body 40 is accommodated in a cylinder bore 12A formed in the housing of a compressor C. The connection part 41 is operation-connected to a swash plate 18 via a shoe 21. A rotation regulating unit 44 to regulate the rotation of the piston 20 around the axis of the piston body 40 by abutting on an inner circumferential surface 11A is provided on the connection part 41. The rotation regulating part 44 is integrated with the piston body 40 via a connection part 45. The piston body 40, the connection part 45 and the rotation regulating part 44 are formed of the same resin, and simultaneouly formed by the same inserting molding process.