PURPOSE: To provide a forming method which has no influence on forming dies by trace vaporized matter and eliminates the need for protective films on the surface of glass blank by coating the surfaces of this glass blank before its forming with soluble films and die contact films and removing both films after the forming.

CONSTITUTION: The front and rear surfaces of the previously preformed glass blank 11, which surfaces come into contact with the forming molds consisting of a material having the yield point higher than the yield point of the glass blank 11, are coated with the soluble films 12 consisting of a water-soluble inorg. compd. at a thickness of 0.2 to 2μm, and further, the surfaces of these films are coated with the die contact films 13 consisting of carbon films or carbide films, etc., not fusible with the forming dies at a thickness of 0.2 to 2μm. The glass blank 11 whose coating is ended is held between the upper and lower forming dies. Pressurizing force is applied on the upper and lower dies in an inert gaseous atmosphere or vacuum under heating to a prescribed temp. and the glass blank 1 formed at a temp. below the glass transition point is taken out. This glass blank is immersed into a melting vessel to elute the soluble films 12 and the die contact films 13 into a solvent. The glass optical element 11 after forming is then taken out.