A nitride semiconductor light emitting device including a light emitting diode and a diode formed on a single substrate, in which the light emitting diode and the diode use a common electrode. According to the present invention, an active layer and a p-type nitride semiconductor layer are each divided into a first region and a second region by an insulative isolation layer, and an ohmic contact layer is formed on the p-type nitride semiconductor layer contained in the first region. A p-type electrode is formed on the ohmic contact layer and is extended to the p-type nitride semiconductor layer contained in the second region. An n-type electrode is formed on the p-type nitride semiconductor layer contained in the second region, passes through the p-type nitride semiconductor layer and the active layer contained in the second region, and is connected to the first n-type nitride semiconductor layer.