Abstract: Projections/depressions of a two-dimensional periodic structure are formed in a p-GaN layer (4) such that the period of the projections/depressions is 1 to 20 times the wavelength of light radiated from an active layer (3) in a semiconductor. As a result, a diffractive effect achieved by the projections/depressions of the two-dimensional periodic structure change the direction in which the light radiated from the active layer (3) travels. If the projections/depressions are not provided, light at a radiation angle which satisfies conditions for total reflection at the interface between a semiconductor device and an air cannot be extracted to the outside of the semiconductor device so that the light emission efficiency of the device is low.