To provide a molding die for manufacturing a metallic optical element which dispenses with polishing processing after press molding of an optical element blank even when manufacturing the metallic optical element having an optical surface of surface roughness Ra of ≤20 nm.

The metallic optical element 1 has a maximum shape error PV of the optical surface 2 of ≤5μm, has a surface roughness Ra of ≤20 nm, contains either one of Al, Cu, Ni, Ag, Zn, Sn, Fe and Ti by 97 mol% or more and has impurities and inevitable impurities besides the same in which the maximum particle size of the impurities is adjusted to 500μm or less. Further, the molding die 13, 16 for finishing the metallic optical element blank for the optical element 1 by molding is formed by using either of cemented carbide, tool steel, cermet and ceramic as the base and has a molding surface 15 of the maximum shape error PV of ≤2μm and the surface roughness Ra of ≤10 nm.

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