PURPOSE: To transfer easily and with high accuracy an optical mirror face of a cavity even when resin is shrinked by generating pressure in resin injected in a process of either injecting curable resin into the cavity, or curing the resin.

CONSTITUTION: Prior to injecting energy hardening resin 3, a mold 1 is faced a mold 2 and clamped by a mold clamping device 6 to form a cavity 7. The mold clamping force is set in a manner of not opening the molds 1 and 2 against the pressure of resin 3 to be generated. Then the resin 3 is injected into the cavity 7 through a resin feed passage 8 communicated with the cavity 7 by an energy curable resin injection device 4. The resin 3 is injected by the amount, in which cure shrinkage is already taken into consideration to generate the pressure in the injected resin 3. An optical mirror face can be transferred efficiently by the arrangement.