Abstract: An image reading device includes a light guiding unit, a pair of light sources, and a light receiving unit. The light guiding unit has incident surfaces, on which light is incident, at both ends, extends in a main scanning direction, and causes light incident on one of the incident surfaces to be reflected, to propagate toward the other of the incident surfaces, and to be applied from a peripheral surface of the light guiding unit onto a document table. The pair of light sources cause light to be incident on the incident surfaces at both the ends of the light guiding unit. The light receiving unit receives, via an optical system, light emitted from the peripheral surface of the light guiding unit and reflected by a document on the document table.