The present invention discloses a linear compressor which can rapidly overcome load and improve compression efficiency, by synchronizing an operation frequency of a linear motor with a natural frequency of a movable member varied by the load and varying a stroke of the movable member according to the load. The linear compressor includes a fixed member having a compression space inside, a movable member linearly reciprocated in the fixed member in the axial direction, for compressing refrigerants sucked into the compression space, one or more springs installed to elastically support the movable member in the motion direction of the movable member, spring constants of which being varied by load, and a linear motor installed to be connected to the movable member, for linearly reciprocating the movable member in the axial direction, and varying a stroke of the movable member according to a predetermined refrigeration force, so that the movable member can be linearly reciprocated to reach a top dead center.