PURPOSE: To suppress the generation of resin scrap and to produce the optical disk having stable quality as there is no flow-in of a photosetting resin by facilitating peeling of even the disk having a large diameter and having poor flexibility, such as glass in particular.

CONSTITUTION: A center block 14 pushes up an inner peripheral part 20a of a disk substrate 20 and a center pin 15 pushes up a slope 290b at the inner peripheral edge of this disk substrate 20 and, therefore, the peeling of the optical disk from a stamper 12 is easy. This center block 14 is formed with a slope 14b on the surface existing in the upper part of the hole for guiding the center block 14 and is interposed with the inner peripheral part 12a of the stamper 12 between this slope 14b and an electromagnetic magnet base 11 and, therefore, the slope 14b and the stamper 12 are in tight contact with each other. The surface 15a of the center block 15 in contact with the slope 20b of the disk substrate 20 is so inclined as to face the slope 20b.