A reciprocating compressor includes a case having a gas suction pipe and a gas discharge pipe. A frame unit is installed in the case and a compression unit, including a cylinder is installed in the frame unit. The compression unit has a plurality of slots formed in a longitudinal direction on its outer circumferential surface. A piston is coupled with a reciprocating motor so as to linearly and reciprocally move into and out of the cylinder and has a plurality of through holes formed at its outer side, communicating with the slots. The compression unit has a gas muffler member installed at an outer circumferential surface of the cylinder.