A substrate W rotates about the center of rotations A0 of a spin base 3, while supported by plural support pins 5 in such a manner that the substrate W can freely slide and while held owing to the force of friction which develops between the bottom surface of the substrate W and the support pins 5. After a detection sensor 74 detects, while the substrate W rotates, an edge surface position (eccentric position) of the edge surface of the substrate which is the farthest from the center of rotations A0, a press block 71 pushes this edge surface position to a preset position P1 which is away along the horizontal direction from the center of rotations A0 by a distance which is determined in accordance with the radius of the substrate W. This aligns the eccentric position to the preset position P1 and positions the center W0 of the substrate within a predetermined range from the center of rotations A0.