1. An image reading apparatus for photoelectrically reading an original image, comprising: an image reading device having a first reading unit for reading a visible image carried by said original image and a second reading unit for reading a reference image in a wavelength different from that used to read said visible image; and a detection device for acquiring correlative pixel distribution information between a visible image signal and a reference image signal using said visible image and said reference image having been read by said image reading device and detecting an image defect caused by a foreign particle deposited on said original image and a flaw of an original using the information.