A substrate is made of a crystallized glass having translucency and an average linear thermal expansion coefficient of −5×10−7/° C. at 30 to 500° C. The substrate has a first surface (working surface) of a smooth surface having a surface roughness Rmax of less than 0.5 μm, and a second surface (non-working surface) of a rough surface having a surface roughness Rmax of 4 μm. A light shielding layer consisting of a light shielding film and an antioxidant film is formed on the second surface of the substrate through sputtering.