An optical element includes: a conductive film having a through opening and a periodic uneven structure (grooves) formed in a surface thereof; and a photonic crystal. The grooves are formed around the through opening, the photonic crystal has an optical waveguide and a defect structure (point defect) optically coupled to the optical waveguide formed therein, the conductive film is disposed opposite to the photonic crystal, and the through opening is opposite to the point defect.