To decrease the irradiation amt. of UV rays without decreasing the reproducing function of information and to decrease damages in a substrate such as deterioration with light or heat by forming a gold film as a reflection film so that the film has enough large reflectance against laser light for reproducing of information and has enough large transmittance for UV rays to harden an adhesive.

This optical disk is obtd. by laminating two disks 10A and 10B each consisting of a transparent substrate 11 and a reflection film 12 formed on the substrate surface with a UV-curing resin adhesive 15. As for the reflection film 12, a gold film is used instead of an aluminum film so that the film 12 has enough large reflectance against laser light of 635 to 650nm wavelength for reproduction of information and enough large transmittance for UV rays of 365nm wavelength to harden the adhesive. Thereby, irradiation amt. of UV rays to harden the adhesive can be decreased without decreasing the information reproducing function, and therefore, damages of a substrate by UV rays such as deterioration by light or heat can be decreased.