A semiconductor laser device comprising a laser oscillation-operating area containing a first cladding layer, an active layer, an optical guiding layer and a second cladding layer in that order, wherein a striped impurity-diffusion region is formed into said second cladding layer from one facet to the other facet and a plurality of narrow strips of GaAs with a spaced pitch are formed in parallel with both facets in the region, except for the region corresponding to said striped diffusion region, which is positioned at the interface between the optical guiding layer and the second cladding layer.