To provide a manufacturing method of an optical element such as a diffraction lens which hardly causes a shape fault in a diffraction structure of a molded article on the occasion of opening a mold.
A plastic lens PL fitted on an optical surface 14a of a movable half 14 is put in an initial release state wherein it is slightly separated from the optical surface 14a, as the result of the peripheral flange portion PLa thereof being pushed outward by ejection pins 16. By initially releasing the plastic lens PL from the movable half 14 immediately after initial mold opening, in this way, it can be avoided completely that a diffraction lens surface PLb formed on the plastic lens PL and a diffraction pattern formed on the optical surface 14a of the movable half 14 come into contact with each other, even when the plastic lens PL contracts by cooling.
HATTORI HIROYUKI
ARAI NORIKAZU
Haruhito Oishi
Yoshihiro Fujimoto