A polarizer of the present invention having a higher level of polarization performance for a light in the deep ultraviolet wavelength range includes: a substrate transparent to deep ultraviolet light; and a periodic structure including a plurality of structural elements at predetermined intervals on the substrate, the polarizer being configured so that the deep ultraviolet light incident thereon is split into a light component reflected by the periodic structure and a light component passing between the structural elements adjacent to each other, and the periodic structure being composed of chromium oxide or tungsten.