A scroll compressor includes a housing; a motor provided in the housing; a rotating shaft rotated by the motor; an orbiting scroll orbitally moved by the rotating shaft; a fixed scroll forming a compression chamber together with the orbiting scroll; and a valve mechanism guiding intermediate pressure refrigerant from an outside of the housing to the compression chamber and discharging refrigerant overcompressed in the compression chamber into a discharge chamber, thereby increasing amount of refrigerant discharged from the compression chamber, and improving performance and efficiency.