A method for treating a mold includes grinding an outer metal surface of a mold body of the mold with a first material; lapping the outer metal surface after the grinding with a second material that is finer than the first material; and polishing the outer metal surface after the lapping to achieve an average surface roughness (R.sub.a) less than or equal to about 0.15 m and a waviness height (W.sub.a) less than or equal to about 100 nm. A mold for shaping glass-based material can include a mold body having an outer metal surface, wherein the outer metal surface has an average surface roughness (R.sub.a) less than or equal to about 0.15 m and a waviness height (W.sub.a) less than or equal to about 100 nm.

An optical element shaping mold set includes a first shaping mold and a second shaping mold that face each other; a tubular third shaping mold which is located around the first shaping mold and the second shaping mold and in which at least one of the first shaping mold and the second shaping mold slides, and heating, pressing and cooling are conducted with a shaping-target material accommodated between the first shaping mold and the second shaping mold, the third shaping mold has a slit formed on at least one of ends in a sliding direction of the at least one of the first shaping mold and the second shaping mold, and the third shaping mold has a linear expansion coefficient that is smaller than a linear expansion coefficient of the first shaping mold and smaller than a linear expansion coefficient of the second shaping mold.

An optical element manufacturing device includes a mold set including: a first shaping mold and a second shaping mold facing each other with a shaping-target material between the first and second shaping molds, and a sleeve located around the first and second shaping molds; and a plurality of stages on which the mold set is conveyed and which heat, press or cool the shaping-target material. The sleeve is conveyed to the stages in such a manner that a conveyance-direction front side of the mold set in an arrangement direction of the plurality of stages has a heat insulation portion with a heat insulation property that is higher than that on a conveyance-direction rear side of the mold set in order to reduce a temperature distribution in the shaping-target material.

An optical element molding mold set includes a first mold and a second mold that are opposite to each other, and a third mold that is located on an outer periphery of a cavity between the first mold and the second mold, and an inner peripheral surface of the third mold has different friction coefficients between one side and another side in an opposite direction of the first mold and the second mold.