PURPOSE: To provide a master disk for a stamper with a resin surface perfectly free from bubbles and defects and having a rugged pattern faithfully transferred from an original die by carrying out replica forming in a vacuum system after holding in the system for a certain time.

CONSTITUTION: A certain amt. of 2P resin 3 is interposed between an original die 1 made of a glass substrate having a rugged pattern 1' and a porous glass substrate 2 and they are put in a transparent chamber 4. This chamber 4 is evacuated to a prescribed internal pressure from the exhaust port 5. After holding at the degree of vacuum for a prescribed time, the 2P resin 3 is cured by irradiation with UV from the substrate side 2 while keeping the degree of vacuum and then the original die 1 is peeled from the porous glass substrate 2.