An air conditioner compressor comprising: a pulley (110-1, 110-2) comprising a plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820); and a clutch (130-1, 130-2) comprising a contact portion comprising the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) in contact with a bottom-end surface of the pulley (110-1, 110-2), wherein the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) is disposed inside the pulley (110-1, 110-2) and comprises an amount of 20 % by volume or greater of a magnetic alloy material on the basis of the total volume of the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820), wherein the magnetic alloy material is ferromagnetic powder and the pulley (110-1, 110-2) is manufactured from an aluminum material, wherein the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) in the clutch (130-1, 130-2) is formed inside a steel material and a shape of a cross-section area of the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) comprises an upper end, on a side toward an electromagnetic induction coil (121-1, 121-2), longer than a lower end, on the opposite side of the upper end, wherein the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) at a thinnest portion of a surface area of the pulley (110-1, 110-2) adjacent to the electromagnetic induction coil (121-1, 121-2) has a thickness of at least 3 mm, wherein the magnetic alloy material includes ferrite magnetic powder comprising iron, cobalt, nickel or alloys thereof, wherein the magnetic alloy material further comprises a rare earth-based magnetic alloy powder, wherein the rare earth-based magnetic alloy material comprises a rare earth-cobalt magnetic powder. a pulley (110-1, 110-2) comprising a plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820); and a clutch (130-1, 130-2) comprising a contact portion comprising the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) in contact with a bottom-end surface of the pulley (110-1, 110-2), wherein the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) is disposed inside the pulley (110-1, 110-2) and comprises an amount of 20 % by volume or greater of a magnetic alloy material on the basis of the total volume of the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820), wherein the magnetic alloy material is ferromagnetic powder and the pulley (110-1, 110-2) is manufactured from an aluminum material, wherein the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) in the clutch (130-1, 130-2) is formed inside a steel material and a shape of a cross-section area of the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) comprises an upper end, on a side toward an electromagnetic induction coil (121-1, 121-2), longer than a lower end, on the opposite side of the upper end, wherein the plastic composite (111-1, 111-2, 131-1, 131-2, 520, 620, 720, 820) at a thinnest portion of a surface area of the pulley (110-1, 110-2) adjacent to the electromagnetic induction coil (121-1, 121-2) has a thickness of at least 3 mm, wherein the magnetic alloy material includes ferrite magnetic powder comprising iron, cobalt, nickel or alloys thereof, wherein the magnetic alloy material further comprises a rare earth-based magnetic alloy powder, wherein the rare earth-based magnetic alloy material comprises a rare earth-cobalt magnetic powder. <EOS>