A method of molding an optical element numerically analyzes the thermal stress produced on a molded optical element product within a mold in a visco-elastic temperature range or elastic temperature range of an optical element material in a cooling step of the molding process on the basis of a visco-elastic characteristic of the optical element material. A correction for the molding face of the mold is made on the basis of the value obtained by the numerical analysis so that any error between the optical functional face of optical element molded by the mold at room temperature and the optical functional face set on design may fall within a tolerance, thereby determining the molding face adapted to the shape of the optical functional face set on design.