Compressor

A compressor comprising:

• a front housing in which a crank chamber is formed;
• a rear housing in which a suction chamber and a discharge chamber are formed;
• a cylinder block disposed between and coupled to the front housing and the rear housing, a plurality of cylinder bores formed in the cylinder block in a circumferential direction, a plurality of pistons reciprocatingly disposed in the plurality of cylinder bores, each of the plurality of pistons having an outer wall formed at a first end of each of the plurality of pistons, the outer wall including a coating layer formed thereon to uniformly maintain a surface of the outer wall, each of the plurality of pistons further including a shoe coupling part formed at a second end of each of the plurality of pistons;
• a rotating shaft is rotatingly supported by the front housing and the cylinder block, and a swash plate is inserted on the rotating shaft;
• and
• a position determination part positioned on one side of the piston, with a conversion point P being a transition between the position determination part and the outer wall, wherein a first axial distance B, from the conversion point P to an end of the outer wall furthest from the conversion point, is shorter than an axis direction length of the outer wall, and a sensor part disposed in the cylinder block, which senses a radial gap distance between the sensor part and the piston, which changes at the conversion point P, to sense a change in position of the position determination part, wherein the sensor senses only the outer wall and the position determination part of the piston and not the shoe coupling part of the piston.