A method for monitoring performance of an eccentricity correction unit, the method includes a first operation of measuring eccentricity of a substrate mounted on a support unit and storing an amount of eccentricity correction corrected by the eccentricity correction unit such that measured eccentricity of the substrate is within a preset allowable eccentricity value, and a second operation of monitoring, based on the stored amount of eccentricity correction, performance degradation of the eccentricity correction unit.