PURPOSE: When a glass lens is formed by pressing a gob in a compression mold, the periphery of the effective aperture is provided with a part which is regulated by the mold and the rest part which does not undergo any restriction in an open state to keep the thickness of the lens pressed constant.

CONSTITUTION: In a glass lens pressing machine, a gap D1 is formed partially along the periphery of the lens openly between male mold 16, female mold 17 and drum mold 18. A lump of softened glass (gob) is pressed with a molding machine consisting of male mold 16, female mold 17 and drum mold 18 to form a lens with a part of the periphery which is regulated by the mold 13 and rest part which is not restricted 14. Thus, glass lenses of constant thickness 11 are formed, even when gobs fluctuate in weights, because excess amounts of gobs are made to flow out of the gap D1.