An improved throughput can be presented, since an influence of the deterioration in crystallinity created in the epitaxial layer can be eliminated by a simple and easy method, and a semiconductor laser device having stabilized properties such as threshold current, slope efficiency, device life time and the like can be presented. A method for manufacturing a semiconductor laser device according to the present invention comprises: forming partially a diffraction grating on a surface of a semiconductor substrate or on a film on the surface of the semiconductor substrate; and forming a multiple-layered film by forming an epitaxial layer on a surface of the diffraction grating. The operation of forming the diffraction grating includes an operation of forming the diffraction grating so that a width of the diffraction grating in a direction that is orthogonal to a cavity direction of the semiconductor laser device is presented as a width equal to or longer than a sum of a mesa width and 30 μm.