There is provided a nitride semiconductor light emitting device capable of inhibiting output deterioration of light emission caused by quality deterioration of a nitride semiconductor layer due to lattice-mismatching between a substrate and the nitride semiconductor layer, and utilizing light traveling to the substrate efficiently, while forming a light emitting device of a vertical type which has one electrode on a back surface of the substrate by using the substrate made of SiC. A light reflecting layer (2) which is formed by laminating low refractive index layers (21) and high refractive index layers (22) having different refractive indices alternately is directly provided on the SiC substrate (1), and a semiconductor lamination portion (5) which is formed by laminating nitride semiconductor layers so as to form at least a light emitting layer forming portion (3) is provided on the light reflecting layer (2). An upper electrode (7) is provided on an upper surface side of the semiconductor lamination portion (5), and a lower electrode (8) is provided on a back surface of the SiC substrate (1).