According to one embodiment, a semiconductor light emitting device includes: a first semiconductor layer; a second semiconductor layer; and a light emitting layer provided between the first and the second semiconductor layers. The first semiconductor layer includes a nitride semiconductor, and is of an n-type. The second semiconductor layer includes a nitride semiconductor, and is of a p-type. The light emitting layer includes: a first well layer; a second well layer provided between the first well layer and the second semiconductor layer; a first barrier layer provided between the first and the second well layers; and a first Al containing layer contacting the second well layer between the first barrier layer and the second well layer and containing layer containing Alx1Ga1-x1N (0.1≦x1≦0.35).