A compressor, comprising: a cylindrical shell; a rotational shaft rotatably mounted in the cylindrical shell; a rotational device comprising a rotor and a stator configured to rotate the rotational shaft; a compression device driven by the rotational shaft; a lower bearing configured to rotatably support one side of the rotational shaft; a lower frame (60; 160) configured to support the lower bearing, the lower frame (60; 160) being configured to be press-fitted into a lower end portion of the cylindrical shell; and a base configured to seal the lower end portion of the cylindrical shell, wherein the lower frame (60; 160) comprises: a main body (61; 161) configured to be press-fitted onto an inner circumferential surface of the cylindrical shell; a flange (66; 166) that extends from the main body (61; 161), the flange (66; 166) being configured to limit a press-fit depth by contacting the lower end portion of the cylindrical shell, and wherein the flange (66; 166) extends from an outer circumferential portion (63; 163) of the main body (61; 161) at a lower end portion thereof; and a mounting portion is formed on the base for mounting the flange (66; 166), wherein the flange (66; 166) is mounted on the mounting portion and wherein the mounting portion comprises a mounting surface that contacts a lower surface (66b; 166b) of the flange (66; 166) and an annular wall that faces an outer circumferential surface of the flange (66; 166), characterized in that a welded portion is formed at a portion defined by the outer circumferential surface of the flange (66; 166), an outer circumferential surface of the shell and an inner circumferential surface of the annular wall. a cylindrical shell; a rotational shaft rotatably mounted in the cylindrical shell; a rotational device comprising a rotor and a stator configured to rotate the rotational shaft; a compression device driven by the rotational shaft; a lower bearing configured to rotatably support one side of the rotational shaft; a lower frame (60; 160) configured to support the lower bearing, the lower frame (60; 160) being configured to be press-fitted into a lower end portion of the cylindrical shell; and a base configured to seal the lower end portion of the cylindrical shell, wherein the lower frame (60; 160) comprises: a main body (61; 161) configured to be press-fitted onto an inner circumferential surface of the cylindrical shell; a flange (66; 166) that extends from the main body (61; 161), the flange (66; 166) being configured to limit a press-fit depth by contacting the lower end portion of the cylindrical shell, and wherein the flange (66; 166) extends from an outer circumferential portion (63; 163) of the main body (61; 161) at a lower end portion thereof; and a mounting portion is formed on the base for mounting the flange (66; 166), wherein the flange (66; 166) is mounted on the mounting portion and wherein the mounting portion comprises a mounting surface that contacts a lower surface (66b; 166b) of the flange (66; 166) and an annular wall that faces an outer circumferential surface of the flange (66; 166), a main body (61; 161) configured to be press-fitted onto an inner circumferential surface of the cylindrical shell; a flange (66; 166) that extends from the main body (61; 161), the flange (66; 166) being configured to limit a press-fit depth by contacting the lower end portion of the cylindrical shell, and wherein the flange (66; 166) extends from an outer circumferential portion (63; 163) of the main body (61; 161) at a lower end portion thereof; and a mounting portion is formed on the base for mounting the flange (66; 166), wherein the flange (66; 166) is mounted on the mounting portion and wherein the mounting portion comprises a mounting surface that contacts a lower surface (66b; 166b) of the flange (66; 166) and an annular wall that faces an outer circumferential surface of the flange (66; 166), characterized in that a welded portion is formed at a portion defined by the outer circumferential surface of the flange (66; 166), an outer circumferential surface of the shell and an inner circumferential surface of the annular wall.