The present invention is aimed at providing an image reading device that
suppresses generation of a so-called edge shadow while suppressing uneven
intensity of light emitted onto an original. A color copy machine 1
includes an illumination portion 347a that irradiates an original G with
light. The illumination portion 347a includes a plurality of LEDs 501
disposed at predetermined intervals in a main scanning direction, an
elliptical diffuser plate 507 that is disposed between the plurality of
LEDs 501 and the original G and causes the light emitted by the plurality
of LEDs 501 to diffuse, and a second reflection mirror 541B that reflects
light, which is a portion of the light diffused by the elliptical
diffuser plate 507 and not directly irradiated onto the original G, so as
to irradiate the light onto the original G.