Patent ID: 7415843

Claim:
A method of manufacturing a glass optical element without a glass trap mark by press-forming a glass material in a chamber by using a forming mold comprising an upper die and a lower die at least one of which is movable, where a surrounded space is formed between the glass material and at least one of the upper die and the lower die when the upper die and the lower die come into contact with the glass material, the method comprising: placing the glass material in the forming mold; reducing a pressure within the chamber before the glass material placed in the forming mold is heated to a press-forming temperature; sealing the space between the glass material and forming surfaces of the mold by applying a load smaller than a pressing load to the glass material when the glass material is in contact with at least one of forming surfaces of the upper and the lower dies, the load smaller than the pressing load being applied by a spring member; then introducing a gas into the chamber in a state where the load smaller than the pressing load is applied to the glass material by the spring member; heating the glass material in the gas; and press-forming the glass material under the pressing load.