In a semiconductor laser device having an oscillation wavelength larger than 760 nm and smaller than 800 nm, at least a lower clad layer, a lower guide layer, an active region, an upper guide layer and an upper clad layer are supported by a GaAs substrate, the active region having a quantum well structure in which one or more well layers and barrier layers are stacked. The one or more well layers and the barrier layers are formed of any one of InGaP, InGaAsP and GaAsP, and the upper and/or lower guide layer is formed of AlzGa1−zAs (0.20