To make the width of a groove narrower and to drastically increase the recording density of an optical disk by recessing one of the groove and a pit from a land surface and protruding the other.

This optical disk is the optical disk provided with the groove 1 and the pit 3, one of the groove 1 and the pit 3 is recessed from the land surface 2 and the other is protruded. Thus, at the time of manufacturing an optical master disk, a part corresponding to a land is exposed by a laser beam and the part corresponding to the pit is exposed by the laser beam. That is, the part corresponding to the groove is not exposed and the part corresponding to the groove is left as a non-exposed part. Thus, in the optical disk, the width of the groove is made smaller than the spot diameter of the laser beam.