A linear compressor, comprising: a piston configured to reciprocate in an axial direction; and a cylinder that is provided on a radially outer side of the piston to accommodate the piston and that defines a compression space with the piston, wherein the cylinder comprises: a gas hole defined at the cylinder such that a first end of the gas hole is at an outer circumferential surface of the cylinder and a second end of the gas hole is at an inner circumferential surface of the cylinder, and a gas pocket that is in communication with the gas hole and that is recessed from the inner circumferential surface of the cylinder, wherein the gas pocket comprises: a first gas pocket provided at a first axial side of the cylinder with respect to a center of an axially extended line; and a second gas pocket provided at a second axial side of the cylinder with respect to the center of the axially extended line, wherein at least one of the first gas pocket or the second gas pocket is elongated in the axial direction of the cylinder, characterized in that a depth of an inner circumferential surface of the gas pocket increases from an edge of the gas pocket to a central portion of the gas pocket, wherein the first gas pocket and the second gas pocket are disposed at different positions in the axial direction of the cylinder. a piston configured to reciprocate in an axial direction; and a cylinder that is provided on a radially outer side of the piston to accommodate the piston and that defines a compression space with the piston, wherein the cylinder comprises: a gas hole defined at the cylinder such that a first end of the gas hole is at an outer circumferential surface of the cylinder and a second end of the gas hole is at an inner circumferential surface of the cylinder, and a gas pocket that is in communication with the gas hole and that is recessed from the inner circumferential surface of the cylinder, a gas hole defined at the cylinder such that a first end of the gas hole is at an outer circumferential surface of the cylinder and a second end of the gas hole is at an inner circumferential surface of the cylinder, and a gas pocket that is in communication with the gas hole and that is recessed from the inner circumferential surface of the cylinder, wherein the gas pocket comprises: a first gas pocket provided at a first axial side of the cylinder with respect to a center of an axially extended line; and a second gas pocket provided at a second axial side of the cylinder with respect to the center of the axially extended line, wherein at least one of the first gas pocket or the second gas pocket is elongated in the axial direction of the cylinder, characterized in that a depth of an inner circumferential surface of the gas pocket increases from an edge of the gas pocket to a central portion of the gas pocket, wherein the first gas pocket and the second gas pocket are disposed at different positions in the axial direction of the cylinder. a first gas pocket provided at a first axial side of the cylinder with respect to a center of an axially extended line; and a second gas pocket provided at a second axial side of the cylinder with respect to the center of the axially extended line, wherein at least one of the first gas pocket or the second gas pocket is elongated in the axial direction of the cylinder, characterized in that a depth of an inner circumferential surface of the gas pocket increases from an edge of the gas pocket to a central portion of the gas pocket, wherein the first gas pocket and the second gas pocket are disposed at different positions in the axial direction of the cylinder.