The present invention provides an image processing apparatus which not only judges the occurrence of multiple feeding with a high accuracy, but also can identify later the location of occurrence of the multiple feeding even if the document reading operation is continued after detecting the occurrence of a multiple feeding. The detection device (the detecting and reading section 53) detects the information storage media attached to the documents which are being fed one sheet at a time by the automatic document feeder 20 and from which the images are being read out. The determining section 56 detects based on the result of this detection the occurrence of multiple feeding in which a plural number of sheets of the document are conveyed in an overlapping state. The information recording section 54 writes the multiple feeding information, indicating that a multiple feeding has occurred, in the information recording medium of the document that was judged to have been fed in an overlapping state.