To provide a method of manufacturing a lens capable of preventing rotation of the lens while suppressing adverse effects on the lens when a gate part is cut.

Since the gate part 12 of a molded product 10 on a first stage 21a is held by a clamp member of a holding device 70 while positioned and is cut, rotation of the gate part 12 can be securely prevented by small force. Namely, when a lens product part 11 is sandwiched from the outer peripheral 11a side, it is not necessarily easy to suppress rotation of the lens product part 11 around an optical axis OA, but when the gate part 12 protruded from the outer periphery 11a of the lens product part 11 is sandwiched, preventive effects of displacement of the gate part 12, that is, rotation of the lens product part 11 can be enhanced by small force, so as to securely prevent scratches on the lens product part 11 and processing failure caused by rotation of the lens product part 11.