An illumination apparatus includes a light source that generates light used for reading an image and a light guide body which extends in a predetermined direction and onto which the light from the light source is incident. The light guide body includes a pair of first faces that reflect the light so as to cause the light to direct to an image reading region from directions different from one another, a second face which emits the light directing from the first faces toward the image reading region and onto which the light reflected from the image reading region is incident, and a third face which emits the light that is incident from the second face and passes between the pair of first faces.