A deflecting unit deflects a plurality of light fluxes from a light source including a plurality of light emitting elements arranged in two-dimensional array. An coupling optical system between the light source and the deflecting unit includes an optical coupling element that collimates the light fluxes and a line-imaging element that images the light fluxes near the deflecting unit in a sub-scanning direction. A holding unit holds the line-imaging element in a state that a position of the line-imaging element is adjusted with respect to a direction parallel to the sub-scanning direction. A scanning optical system condenses the deflected light fluxes on the scanning surface.