An optical scanning device includes: light sources emitting first beams having colors; a beam splitting unit splitting the first beams into second beams; a deflecting unit including reflecting members, each corresponding to one of the second beams and each performing deflection scanning of the second beams; an optical system for image formation of the second beams scanning on target surfaces that have been assigned with colors corresponding to the first beams; a detecting unit for detecting which of the reflecting member corresponds to the second beam; an interchanging unit for obtaining data of a lines corresponding to each of the first beams and interchanging the data of the lines based on a detection result; and a light source control unit for controlling the light sources in such a way that the light sources emit the first beams in accordance with the data of the lines interchanged.