PURPOSE: To effectively prevent peeling of a protective film layer by forming the protective film layer' in a manner that the edge part of the film is hardly influenced by external conditions.

CONSTITUTION: A groove layer 2 of a thick film having smaller diameter than the outer diameter of a substrate 1 is formed on a disk substrate 1. A recording layer 3 is formed on the groove layer 2, on which an org. resin liquid comprising a UV-curing resin is uniformly applied by roll coating and cured to form a protective film layer 4. In this method, the groove layer 2 is made rather thick as about ≥50μm, and the groove layer and the recording layer 3 are made to have smaller outer diameter than that of the disk substrate 1 to form a step part S1 on the circumferential edge of the disk substrate 1. Thereby, the org. protective film layer 4 does not extend to the outer circumferential edge of the substrate 1.