A light emitting device having a simple structure that can be easily manufactured, attaining high light emitting efficiency stably for a long time is obtained, which light emitting device includes: a GaN substrate as a nitride semiconductor substrate and, on a first main surface of the nitride semiconductor substrate, an n-type AlxGa1-xN layer, a p-type AlxGa1-xN layer positioned further than the n-type AlxGa1-xN layer viewed from the nitride semiconductor substrate, and a quantum well positioned between the n-type AlxGa1-xN layer and the p-type AlxGa1-xN layer. In the light emitting device, specific resistance of the nitride semiconductor substrate is at most 0.5 Ω·cm, the side of p-type AlxGa1-xN layer is mounted face-down, and the light is emitted from the second main surface 1a that is opposite to the first main surface of the nitride semiconductor substrate. The second main surface 1a of nitride semiconductor substrate has trenches formed therein.