An image reading device includes: a foreign-matter image position detection unit that detects a predetermined foreign-matter image from the image read by a document reading unit when the document conveyed by a document conveying unit comes off from a document reading position and detects a main scanning direction position of the foreign-matter image in the main scanning direction; and a lighting control unit that lights up the light-emitting element group arranged in the main scanning direction and lights up the light-emitting elements within a predetermined range from the main scanning direction position of the foreign-matter image in a light emission mode that is different from a light emission mode of other light-emitting elements when the foreign-matter image is detected by the foreign-matter image position detection unit.