Centering device, centering method and substrate processing apparatus

A substrate supported on a substrate support is surrounded by a first contact member located at a first reference position, a second contact member located at a second reference position and a third contact member located at a third reference position in the horizontal plane. These three contact members gradually approach the substrate while keeping distances from a center of the substrate support equal by repeating the minute movements. The substrate posture is so adjusted that the direction of eccentricity is parallel to the virtual line prior to the start of the movements of the contact members. In the invention, the substrate posture is so adjusted that the direction of eccentricity is parallel to the virtual line prior to the above centering of the substrate.