The present invention relates to a III-nitride semiconductor light emitting device comprising a plurality of III-nitride semiconductor layers including an active layer emitting light by recombination of electrons and holes, the plurality of III-nitride semiconductor layers having a p-type III-nitride semiconductor layer at the top thereof, an SiaCbNc (a≧0,b>0,c≧0,a+c>0) layer grown on the p-type III-nitride semiconductor layer, the SiaCbNc (a≧0,b>0,c≧0,a+c>0) layer having an n-type conductivity and a thickness of 5 Å to 500 Å for the holes to be injected into the p-type III-nitride semiconductor layer by tunneling, and a p-side electrode formed on the SiaCbNc (a≧0,b>0,c≧0,a+c>0) layer. Generally, in III-nitride semiconductor light emitting devices, if a p-side electrode is formed directly on a p-type nitride semiconductor, high contact resistance is generated due to a high energy bandgap and low doping efficiency of the p-type nitride semiconductor. This makes the efficiency of the device degraded. According to the present invention, however, a SiaCbNc (a≧0,b>0,c≧0,a+c>0) layer which can be doped with a high concentration is intervened between a p-type nitride semiconductor and a p-side electrode. Therefore, the present invention can solve the conventional problem.