A semiconductor laser having an n-cladding layer, an optical guide layer, an active layer, an optical guide layer, and a p-cladding layer above an InP substrate, in which the active layer has a layer constituted with Be-containing group II-VI compound semiconductor mixed crystals, and at least one of layers of the n-cladding layer, the optical guide layer, and the p-cladding layer has a layer constituted with elements identical with those of the Be-containing group II-VI compound semiconductor mixed crystals of the active layer, and the layer is constituted with a superlattice structure comprising, as a well layer, mixed crystals of a Be compositions with the fluctuation of the composition being within ±30% compared with the Be composition of the group II-VI compound semiconductor mixed crystals of the active layer, whereby the device characteristics of the semiconductor laser comprising the Be-containing group II-VI compound semiconductor matched with the InP substrate.