PURPOSE: To obtain the titled duplicate in which a fine air bubble does not mix in a resin layer and a dropout is scarce, by arranging a base plate opposing to a mold, reducing the pressure of a clearance part, casting a radiation curable resin and curing the resin layer by irradiating with a radiation.

CONSTITUTION: The base plate 4 having a radiation transparency is opposed to a mold 1 and its one face is contacted to a mold cover 5 and the central part of its opposite face is contacted to the film thickness regulating protrusion 6 provided at a central pin 3. A clearance 8 is made the state of a pressure lower than an atmospheric pressure (an amount of pressure reduction of ca. 30W60cm Hg) by an aspiration, evacuation with a vacuum pump via an evacuation port 10. A radiation curable resin is cast in the clearance 8 via a resin passage 9, a molding resin layer 11 is shaped at the entire face of the information signal face of the mold 1, then it is irradiated with the proper amount of a radiation from a radiation source 12 and the molding resin layer 11 is cured and integrated with the base plate 4. The molding resin layer 11 integrated with the base plate 4 is stripped from the mold 1, obtaining a duplicated disk.