Preventing a molded disc substrate from generating a separation pattern. To this end, a molding die 1 includes a pair of stationary die 6 and movable die 7, and an outer circumference ring 16 for molding an outer circumference end of the disc substrate 2. The outer circumference ring 16 is so mounted as to be movable along forward and backward directions in parallel with a moving direction of the movable die 7 toward the stationary die 6, and has a retaining surface 39 for retaining the outer circumference of the molded disc substrate 2.