AN OPTICAL DISC

摘要

In an optical disc according to the present invention, first (5) and second (8) discs comprise a hub half (14) inserted into the center portion of a disc substrate respectively, the hub half (14) is arranged at the center of the disc substrate, and a recording layer (9) is formed on the disc substrate by using the center portion of the hub half as a reference point. Therefore, the center of the recording layer can not be shifted from the center of the hub half and the optical disc with high reliability can be provided when recording and playing back an information.