A linear compressor, comprising: a shell; a cylinder provided in the shell to define a compression space for a refrigerant; a piston reciprocated in an axial direction within the cylinder; a discharge valve provided at one end of the cylinder to selectively discharge the refrigerant compressed in the compression space; at least one nozzle disposed in the cylinder to introduce at least a portion of the refrigerant discharged through the discharge valve into the cylinder; and a frame coupled to an outside of the cylinder; a passage to guide the refrigerant discharged from the discharge valve into the at least one nozzle, wherein the passage is defined between an outer circumferential surface of the cylinder and an inner circumferential surface of the frame, the cylinder comprising: a cylinder body comprising the at least one nozzle, the cylinder body having a cylindrical shape; and a cylinder flange that extends outward from the cylinder body in a radial direction, the frame comprising: a frame body that surrounds the cylinder body; and a recess into which the cylinder flange is inserted, and a seat that extends inward from the recess in the radial direction and on which a seat surface of the cylinder flange is seated, and the passage comprising a second passage defined between the seat and the seat surface of the cylinder flange, a filter having a ring shape and being installed in the second passage, the filter comprising a felt formed of polyethylene terephthalate fiber or an adsorption paper, wherein the cylinder flange pushes the filter when the filter is seated on the seat and the cylinder is coupled to the frame. a shell; a cylinder provided in the shell to define a compression space for a refrigerant; a piston reciprocated in an axial direction within the cylinder; a discharge valve provided at one end of the cylinder to selectively discharge the refrigerant compressed in the compression space; at least one nozzle disposed in the cylinder to introduce at least a portion of the refrigerant discharged through the discharge valve into the cylinder; and a frame coupled to an outside of the cylinder; a passage to guide the refrigerant discharged from the discharge valve into the at least one nozzle, wherein the passage is defined between an outer circumferential surface of the cylinder and an inner circumferential surface of the frame, the cylinder comprising: a cylinder body comprising the at least one nozzle, the cylinder body having a cylindrical shape; and a cylinder flange that extends outward from the cylinder body in a radial direction, a cylinder body comprising the at least one nozzle, the cylinder body having a cylindrical shape; and a cylinder flange that extends outward from the cylinder body in a radial direction, the frame comprising: a frame body that surrounds the cylinder body; and a recess into which the cylinder flange is inserted, and a seat that extends inward from the recess in the radial direction and on which a seat surface of the cylinder flange is seated, and the passage comprising a second passage defined between the seat and the seat surface of the cylinder flange, a filter having a ring shape and being installed in the second passage, the filter comprising a felt formed of polyethylene terephthalate fiber or an adsorption paper, wherein the cylinder flange pushes the filter when the filter is seated on the seat and the cylinder is coupled to the frame. a frame body that surrounds the cylinder body; and a recess into which the cylinder flange is inserted, and a seat that extends inward from the recess in the radial direction and on which a seat surface of the cylinder flange is seated, and the passage comprising a second passage defined between the seat and the seat surface of the cylinder flange, a filter having a ring shape and being installed in the second passage, the filter comprising a felt formed of polyethylene terephthalate fiber or an adsorption paper, wherein the cylinder flange pushes the filter when the filter is seated on the seat and the cylinder is coupled to the frame.