A nitride semiconductor light emitting device and a method of manufacturing the same are disclosed. The nitride semiconductor light emitting device comprises an n-type nitride semiconductor layer formed on a substrate, an active layer formed on the n-type nitride semiconductor layer, a p-type nitride semiconductor layer formed on the active layer, an undoped GaN layer formed on the p-type nitride semiconductor layer, an AlGaN layer formed on the undoped GaN layer to form a two-dimensional electron gas (2DEG) layer at a bonding interface between the AlGaN layer and the undoped GaN layer, and an n-side electrode and a p-side electrode respectively formed on the n-type nitride semiconductor layer and the AlGaN layer to be connected to each other. As a hetero-junction structure of GaN/AlGaN is formed on the p-type nitride semiconductor layer, contact resistance between the p-type nitride semiconductor layer and the p-side electrode is enhanced by virtue of tunneling effect through the 2DEG layer.