A semiconductor light-emitting element includes a substrate and a semiconductor stack portion provided on the substrate and having at least a first-conductivity-type semiconductor layer, a light-emitting layer, and a second-conductivity-type semiconductor layer. The substrate has a property to allow transmission of light from the light-emitting layer, and has a hexahedral shape including a first surface on which a semiconductor stack portion is provided, a second surface located opposite to the first surface, a pair of third surfaces orthogonal to the first surface and the second surface, and a pair of fourth surfaces orthogonal to the first surface and the second surface and different from the pair of third surfaces.