A semiconductor laser comprises a window structure part including a low resistance active layer formed in end face regions, to have a lower resistance than an active layer located inward with respect to the end face regions. A length between the front end of the contact layer and the front end face is longer by 10 μm or more than a length of a front-end-face side window structure part, and is shorter than a length between the front end face and the rear end of the contact layer. A length between an end of a rear side electrode on the side of the front end face and the front end face is 1.2 times or more a substrate thickness of a substrate, and is shorter than a length between the front end face and an end of the rear side electrode on the side of the rear end face.