An image reading device includes: a transport path; a reading member that reads an image of a document at a reading position on the transport path, and that includes a light source movable with respect to the reading position in a sub scanning direction which extends along a document transport direction and being capable of reading at positions in the vertical scanning direction; a reflecting member that has a reflecting surface that faces the reading member; a movement controller that controls the reading member so as to move the light source with respect to the reading position before the document is transported to the reading position when the reading member reads the image; a dust determination unit that determines presence of dust; and an announcement member that announces presence of dust to a user when dust is present.