A silicon substrate has a protective film formed on each side. A semiconductor surface opening not smaller than a given region is formed by removing the protective film. A through-hole having an inner size smaller than the given region is formed in the opening by laser machining. Thereafter, the inner size of the through-hole is increased by anisotropic etching, and the etching is ended when the inner size of the through-hole reaches the given size. In this way, a through-hole of a given size can be formed without allowing reversely tapered crystal planes to appear from a surface of the substrate toward the inside of the through-hole.