A linear compressor is provided that may include a casing, a compressor body accommodated in the casing and defining a compression space for a refrigerant, a suction pipe coupled to a first side of the casing to supply the refrigerant to the compression space, a discharge pipe coupled to a second side of the casing to discharge the refrigerant compressed in the compression space outside of the casing, a process pipe coupled to the second side of the casing spaced apart from the discharge pipe to inject a refrigerant for supplement into the casing, and a separator that separates a mixed fluid of a refrigerant and oil injected through the process pipe.