An insulation film 150 made of SiO₂ is formed on a p-type layer 106, and a multiple thick film positive electrode 120, which is a metal film formed through metal deposition, is formed on the insulation film 150 and on the p-type layer 106 at the central portion of which has a window and is exposed. The insulation film 150 has a thickness of one fourth multiple of emission wavelength. Thickness of the insulation film 150 is generally determined by multiplying one fourth of intramedium emission wavelength by an odd number. By interference effect, directivity of radiated light along the optical axis direction can be improved.