A semiconductor light emitting device of one embodiment includes: a substrate; an n-type layer of an n-type nitride semiconductor on the substrate; an active layer of a nitride semiconductor on the n-type semiconductor layer; a p-type layer of a p-type nitride semiconductor on the active layer. The p-type layer has a ridge stripe shape. The device has an end-face layer of a nitride semiconductor formed on an end face of the n-type semiconductor layer, the active layer, and the p-type semiconductor layer. The end face is perpendicular to an extension direction of the ridge stripe shape. The end-face layer has band gap wider than the active layer. The end-face layer has Mg concentration in the range of 5E16 atoms/cm3 to 5E17 atoms/cm3 at a region adjacent to the p-type layer.