An image reading device includes a light source, an imaging section, and a controller. The light source includes a plurality of light emitting elements. The light source irradiates light to an original document, while moving relative to the original document. The imaging section obtains scan data read from the original document by light irradiated to the original document from the light source. The controller controls the light source and the imaging section. The controller determines a read target region and a non-read target region in the original document, turns on a light emitting element out of the plurality of light emitting elements, which corresponds to the read target region, and turns off a light emitting element out of the plurality of light emitting elements, which corresponds to the non-read target region.