1. An imaging apparatus comprising: an optical elements that disperses an incoming light from a subject into a first light composed of wavelength components in a visible light region only, and a second light which does not contain the first light and which is composed of wavelength components in other than visible light region only; a color image pickup device that receives the first light irradiated from the optical element; and a monochrome image pickup device that receives the second light irradiated from the optical element.