a compressor including a bearing, the bearing supporting a rotating shaft;

a sensor configured to measure an index value correlated with a movement of the rotating shaft, the movement of the rotating shaft being made while the compressor is in operation; and

a controller configured to detect a degree of wear of the bearing based on the measured index value obtained by the sensor,

wherein the bearing is a plain bearing, and the bearing includes a cylindrical backing metal part and a cylindrical alloy part provided on an inner side of the cylindrical backing metal part and has a plurality of air gaps provided in an outer circumferential surface of the cylindrical alloy part of the bearing and arranged at intervals in a circumferential direction of the bearing such that the degree of wear of the bearing changes a positional relationship between an inner circumferential surface of the bearing and the plurality of air gaps and eventually changes a shape of the inner circumferential surface of the bearing, and

wherein the controller is configured to detect the degree of wear of the bearing based on a change in the measured index value that is caused by a change in the shape of the inner circumferential surface of the bearing.