A light scanning device having a light source being electrically ON/OFF controlled, deflection member such as a polygon mirror for deflecting light emitted from the light source to perform scanning operation, a first lens for correcting scanning speed of light deflected by the deflection member on a scanning surface, a second lens for correcting astigmatism of the first lens and/or for compensating tilt of the surface of the polygon mirror, a base plate for separately mounting thereon the first and second lenses with predetermined positional relations, and a housing case for mounting thereon the light source, the deflection member and the base plate with predetermined positional relations. The first and second lenses are seated on the base plate in such a fashion that they satisfy the positional relations with other optical components when the base plate is installed on the housing case. The position of the second lens on the base plate is separately adjusted with placing the base plate on an adjusting device so as to prove sufficient optical performance required for light scanning operation.