A semiconductor laser apparatus can improve electric conversion efficiency to a satisfactory extent. The apparatus includes an n-type cladding layer, an n-type cladding layer side guide layer, an active layer, a p-type cladding layer side guide layer, and a p-type cladding layer, wherein electrons and holes are injected into the active layer, transverse to the active layer, through the n-type cladding layer side guide layer and the p-type cladding layer side guide layer. The p-type cladding layer side guide layer is thinner than the n-type cladding layer side guide layer to position the active layer closer to the p-type cladding layer, and, at the same time, the refractive index of the p-type cladding layer side guide layer is higher than the refractive index of the n-type cladding layer side guide layer.