To provide a reciprocating compressor in which leak of gas from a piston ring is not avoidable and leaking gas can be automatically recovered into a suction gas flow passage after cooling.

Leaking gas from a piston seal part is recovered by providing a communication passage 14 always making communication between an upstream of a check valve 10 provided in the suction gas flow passage 12 and a non-compression side 7 of a cylinder, and a seal part 5 of a piston rod.