A semiconductor laser device includes a cavity extending in a propagation
direction of a laser beam (X-direction). A front facet is on one end of
the cavity through which the laser beam is emitted. A rear facet is on
the other end of the cavity. An anodic oxide film is provided on at least
one of the front facet and the rear facet, and the anodic oxide film
preferably has a thickness of .lamda./4n or an odd integer multiple
thereof, where .lamda. is the wavelength of the laser beam and n is the
refractive index of the anodic oxide film.