According to one embodiment, a semiconductor light emitting device includes a first semiconductor layer, a second semiconductor layer and a light emitting part. The first semiconductor layer includes an n-type semiconductor layer. The second semiconductor layer includes a p-type semiconductor layer. The light emitting part is provided between the first semiconductor layer and the second semiconductor layer, and includes a plurality of barrier layers and a well layer provided between the plurality of barrier layers. The first semiconductor layer has a first irregularity and a second irregularity. The first irregularity is provided on a first major surface of the first semiconductor layer on an opposite side to the light emitting part. The second irregularity is provided on a bottom face and a top face of the first irregularity, and has a level difference smaller than a level difference between the bottom face and the top face.