The present disclosure relates to a compressor including a case, a compression unit provided inside the case, and a driving unit, wherein the compression unit includes a cylinder having a compression space, a piston reciprocating inside the cylinder, a discharge cover covering the compression space, a first plenum disposed inside the discharge cover and having a discharge space and a coupling space, a second plenum disposed inside the discharge cover and defining a movement channel through which refrigerant moves, a rib disposed in the movement channel, and a communicating portion through which the discharge space and the movement channel communicate with each other, wherein the refrigerant discharged from the compression space moves along the discharge space, the communicating portion, and the movement channel, whereby pulsation caused by the discharge of the refrigerant can be reduced.