An optical element manufacturing apparatus is provided with a fixed side metal mold 5 attached to a fixed platen 1, and a movable side metal mold 6 attached to a movable platen 2. The fixed side metal mold 5 and the movable side metal mold 6 are clamped by bringing both platens 1 and 2 close to each other. In the clamped status, a molding material is injected into a molding cavity between the both metal molds and an optical element is produced. A taper recessed section 11a and a taper protruding section 21a, provided on the fixed side metal mold 5 and the movable side metal mold 6 respectively, fit each other. The movable side metal mold 6 provides a friction mechanism section 23 which permits the metal mold to shift within a plane perpendicular to the clamping direction with respect to the movable platen 2.