There is provided a high-efficient molding method for realizing an inexpensive optical element exhibiting environmental stability of optical performance approximately equivalent to glass optical elements. Optical plate 71p which is a transparent inorganic material with stable optical property in the environment, is inserted in molding cavity CV. Then, molds 61 and 62 are closed and optical plate 71p is unitedly molded with energy curable resin to obtain molded body MP. Thereby, optical path length of the energy curable resin is shortened, and the optical property of the molded body MP is hardly affected by environmental change. A highly accurate molding transferability of the shape of optical surfaces 71j and 71k formed by injection molding, simultaneous molding of the opposing optical surfaces 71j and 71k, and securing alignment of the double-molded optical surfaces 71j and 71k are easily realized. Therefore, inexpensive optical element 71a can be molded with high efficiency.