An optical disk having a recording layer on a substrate, a bonding layer which is made of an ultraviolet cured resin bonding the recording layer, a transparent layer which is bonded to the bonding layer, and an overcoating layer which is formed on the transparent sheet and is made of the ultraviolet cured resin further has a mixed layer which is formed by mixing the ultraviolet cured resins of the bonding layer and the overcoating layer. Consequently, the bonding layer, the overcoating layer, and the mixed layer are integrally cured, so that the substrate is entirely covered with the ultraviolet cured resin having transparency, which allows a light transmitting layer A to be protected with sufficient strength.