According to one embodiment, a semiconductor light emitting device includes first and second semiconductor layers, and a light emitting unit. The light emitting unit is provided between the first and second semiconductor layers and includes well layers and barrier layers. The barrier layers include p-side and n-side barrier layers, and a first intermediate barrier layer. The n-side barrier layer is provided between the p-side barrier layer and the first semiconductor layer. The first intermediate barrier layer is provided between the barrier layers. The well layers include p-side and n-side well layers, and a first intermediate well layer. The p-side well layer is provided between the p-side barrier layer and the second semiconductor layer. The n-side well layer is provided between the n-side barrier layer and the first intermediate barrier layer. The first intermediate well layer is provided between the first intermediate barrier layer and the p-side barrier layer.