A semiconductor laser (101) includes a first cladding layer (103), an active layer (105) and a second cladding layer (108). A window region (115) including fluorine, that is, an impurity element with higher electronegativity than nitrogen, is formed in the vicinity of a front end face (113) and a rear end face (114) of a laser resonator. The window region (115) is formed by exposing the front end face (113) and the rear end face (114) to carbon fluoride (CF.sub.4) plasma. The effective band gap of a portion of the active layer (105) disposed in the window region (115) is larger than the effective band gap of another portion of the active layer, and hence, it functions as an end face window structure for suppressing COD.