The semiconductor laser device includes a cavity structure having a first clad layer, an active layer and a second clad layer formed on a substrate. The second clad layer has a stripe portion extending between the front end face from which laser light is extracted and the rear end face opposite to the front end face. The stripe portion has a first region located closer to the front end face, a second region located closer to the rear end face and a change region whose width changes located between the first and second regions. The effective refractive index difference between the inside and outside of the stripe portion in the change region is greater than that in the first region.