PURPOSE: To obtain the lens of accurate shape and size by charging fluid resin in a mold and rotating it, cooling resin under effect of centrifugal force.

CONSTITUTION: A sprue 4 and a sprue 6 are connected at the condition of stopping rotation of the upper mold 1 and the lower mold 2 and fluid resin is filled by injection into the molding cavity 3 through these sqrues. Then, the upper mold 1 and the lower mold 2 are rotated as one body around the optical axis 0. Rotational velocity is made so as to exert sufficient centrifugal force on the injected resin. When resin is cooled, rotation of the mold is stopped, molding is finished. By this, the shape of the mold is transferred with fidelity and the accurate lens is obtained.