An image reading device includes: a CCD for reading an image on a document to output an image signal; a light source for switchingly emitting visible light and non-visible light; and lighting control means for controlling lighting periods of the light source. The lighting control means is adapted to perform control such that a first light source lighting period for applying non-visible light is longer than a second light source lighting period for applying visible light. The image reading device also includes splitting means for splitting the image signals outputted from the CCD into an image signal upon application of visible light and an image signal upon application of non-visible light.