PURPOSE: To prevent failures due to immersion of polishing liquid in a rear surface polishing process, and enable the yield to be improved by applying a glass substrate having stages in the utmost peripheries in stamper forming surfaces and being thinner than the central part in the thickness of utmost peripheries.

CONSTITUTION: Glass substrate holding mechanisms 2 in a spatter device as a conductive device are to hold staged parts, and the glass substrate is adhered with a conductive film in order to form a uniform electrocast film 5. Namely, Ni particles being a spatter component in the conductive process come in and adhere not only to the surface (a stamper forming surface) of the glass substrate 1, but also to the staged parts, and thus the electrocast film 5 is formed on the conductive film thereof.