A compressor comprising: a casing including a discharger for discharging a refrigerant on one side; a drive unit coupled to an inner circumferential face of the casing to rotate a rotation shaft; and a compression unit coupled to the rotation shaft to compress the refrigerant, wherein the compression unit includes: an orbiting scroll coupled to the rotation shaft to orbit based on that the rotation shaft rotates; a fixed scroll engaged with the orbiting scroll, wherein the fixed scroll is provided to receive the refrigerant, and compress and discharge the refrigerant; a main frame seated on the fixed scroll and accommodating the orbiting scroll therein, wherein the rotation shaft is provided to pass through the main frame; and an Oldham's ring coupled to the orbiting scroll and the main frame to prevent rotation of the orbiting scroll, wherein the Oldham's ring includes: a ring body disposed between the orbiting scroll and the main frame; a plurality of keys protruding from the ring body and coupled to the orbiting scroll and the main frame; and a cap including a coupling hole therein for accommodating each key therein, wherein the cap is disposed to be inserted into the main frame, wherein the coupling hole further includes: a machined portion spaced apart from at least a portion of an outer surface of the key, characterized in that the ring body includes an inclined portion formed at a portion where each of the plurality of keys protrudes such that the ring body is spaced apart from the cap. a casing including a discharger for discharging a refrigerant on one side; a drive unit coupled to an inner circumferential face of the casing to rotate a rotation shaft; and a compression unit coupled to the rotation shaft to compress the refrigerant, wherein the compression unit includes: an orbiting scroll coupled to the rotation shaft to orbit based on that the rotation shaft rotates; a fixed scroll engaged with the orbiting scroll, wherein the fixed scroll is provided to receive the refrigerant, and compress and discharge the refrigerant; a main frame seated on the fixed scroll and accommodating the an orbiting scroll coupled to the rotation shaft to orbit based on that the rotation shaft rotates; a fixed scroll engaged with the orbiting scroll, wherein the fixed scroll is provided to receive the refrigerant, and compress and discharge the refrigerant; a main frame seated on the fixed scroll and accommodating the orbiting scroll therein, wherein the rotation shaft is provided to pass through the main frame; and an Oldham's ring coupled to the orbiting scroll and the main frame to prevent rotation of the orbiting scroll, wherein the Oldham's ring includes: a ring body disposed between the orbiting scroll and the main frame; a plurality of keys protruding from the ring body and coupled to the orbiting scroll and the main frame; and a cap including a coupling hole therein for accommodating each key therein, wherein the cap is disposed to be inserted into the main frame, wherein the coupling hole further includes: a machined portion spaced apart from at least a portion of an outer surface of the key, characterized in that the ring body includes an inclined portion formed at a portion where each of the plurality of keys protrudes such that the ring body is spaced apart from the cap. an Oldham's ring coupled to the orbiting scroll and the main frame to prevent rotation of the orbiting scroll, wherein the Oldham's ring includes: a ring body disposed between the orbiting scroll and the main frame; a plurality of keys protruding from the ring body and coupled to the orbiting scroll and the main frame; and a cap including a coupling hole therein for accommodating each key therein, wherein the cap is disposed to be inserted into the main frame, wherein the coupling hole further includes: a machined portion spaced apart from at least a portion of an outer surface of the key, characterized in that the ring body includes an inclined portion formed at a portion where each of the plurality of keys protrudes such that the ring body is spaced apart from the cap. a ring body disposed between the orbiting scroll and the main frame; a plurality of keys protruding from the ring body and coupled to the orbiting scroll and the main frame; and a cap including a coupling hole therein for accommodating each key therein, wherein the cap is disposed to be inserted into the main frame, wherein the coupling hole further includes: a machined portion spaced apart from at least a portion of an outer surface of the key, characterized in that the ring body includes an inclined portion formed at a portion where each of the a machined portion spaced apart from at least a portion of an outer surface of the key, characterized in that the ring body includes an inclined portion formed at a portion where each of the plurality of keys protrudes such that the ring body is spaced apart from the cap.