An optical member to be arranged in an optical path of a light, includes an optical medium made of an insulator or a semiconductor; a first element provided at a first position in the optical medium and made of a first electric conductor having a width approximately same as or smaller than a wavelength of the light, the first position being a position in the optical path; and a second element provided at a second position, in the optical medium, different from the first position, and made of a second electric conductor having a width approximately same as or smaller than the wavelength of the light, the second position being a position in the optical path.