Abstract: An illumination device includes plural lamps a prism, a first lens array, and a second lens array, wherein the first lens array is formed such that images of the lamps are formed a predetermined space apart from each other on a lens, which corresponds to a predetermined lens among plural lenses of a second lens array, by light from the lamps having passed the predetermined lens of the first lens array. All or a part of plural images formed by a lens separate from the predetermined lens of the first lens array are practically arranged among the formed images of the lamps. And the second lens array is formed such that the images formed on the second lens array are irradiated on a light-receiving surface in a predetermined relation.