An light irradiation system for irradiating light a document face includes a light source; a light guiding member to guide light emitted from the light source; and a reflector to reflect a part of light exiting from the light guiding member to the document face. A direction that emission light intensity of the light emitted from the light source becomes the strongest is different from a direction extending from the light source to an irradiation area. The irradiation area is irradiated by a reflection light reflected by the reflector, and a direct light exiting from the light guiding member without reflection at the reflector. The light guiding member including an incidence surface, an exit surface, and a light guiding part including a total reflection face. Light quantity irradiated to the document face by reflection light is smaller than light quantity irradiated to the document face by direct light.
