The invention provides a
semiconductor laser device with good temperature characteristic, high polarization rate and high
refraction light output. A
semiconductor laser device includes an n-type clad layer, an
active layer, and a p-type clad layer having a
ridge and wing regions. The wing regions are provided with a first trench present on one side of the
ridge and a second trench provided on the other side thereof being interposed therebetween. A
reflectivity Rf at a front end face of a
resonator, a
reflectivity Rr at a rear end face of the
resonator, a minimum value W1 of a width of the first trench in a region adjacent to the front end face, a minimum value W2 of a width of the second trench in the region adjacent to the front end face, a width W3 of the first trench at the rear end face, and a width W4 of the second trench at the rear end face satisfy Rf<Rr, W1<W3, and W2<W4. A width Wf of the
ridge at the front end face, and a width Wr of the ridge at the rear end face satisfy Wf>Wr. The ridge includes a region where a width decreases with distance from the front end side toward the rear end side.