A plurality of image-forming optical elements are disposed such that a part of a field-of-view region of one image-forming optical element overlaps a part of a field-of-view region of an image-forming optical element disposed adjacent to the one image-forming optical element, each of the image-forming optical elements includes: a lens for collecting light scattered by a reading object; an aperture stop for cutting off some of the light collected by the lens; a phase modulating element for modulating phase of light passing through the aperture stop; and a lens for allowing the light whose phase is modulated by the phase modulating element to form an image on an image-forming surface, and the phase modulating elements are loaded such that resolution characteristics of the phase modulating elements in an arrangement direction of the image-forming optical elements are the same among the image-forming optical elements.