To provide a semiconductor laser that suppresses end face destruction due to catastrophic optical damage (COD) to a light emission end face and has high output characteristics.An n-type clad layer, a current block layer, an active layer, and a p-type clad layer are provided over an n-type substrate whose major plane has an off-angle in a direction from a (0001) plane. For example, the current block layer is arranged on both sides of a current constriction area. Then, the current block layer is arranged so as to be retracted from a cleavage plane (line). In this case, in the active layer having a quantum well structure that is crystal-grown over the n-type clad layer and the current block layer, the layer thickness of a window area from the cleavage plane (line) up to the end part of the current block layer is smaller than the layer thickness of the current constriction area (area between the current block layers). As a result, the band gap of the active layer in the window area becomes large, and thus it is possible to suppress end face destruction due to the COD.