A semiconductor light-emitting device including an N-type semiconductor layer, a plurality of P-type semiconductor layers, a light-emitting layer, and a contact layer is provided. The light-emitting layer is disposed between the N-type semiconductor layer and the whole of the P-type semiconductor layers. The P-type semiconductor layers are disposed between the contact layer and the light-emitting layer. All the P-type semiconductor layers between the light-emitting layer and the contact layer include aluminum.