In an optical scanner for reducing shading, a semiconductor laser or a semiconductor laser array is set to a light source and a laser beam from the light source is deflected by a light deflector having a deflecting reflecting face and is converged by a lens for scanning as a light spot on a scanned face to perform an optical scanning operation. The optical scanner comprises one or more bending mirrors for bending an optical path of the laser beam and arranged between the light deflector and the scanned face; and an increased reflecting coating film disposed on a mirror face of the one or more mirrors such that reflectivity is gradually increased from a central portion of the increased reflecting coating film in a main scan-corresponding direction toward both end portions of the film.