To easily judge the occurrence of an image defect and abnormality due to a stain caused to a document read part and to easily and securely perform cleaning by placing a printing means in operation to print abnormality information out when shading data are abnormal.

A white pressure plate 3 is used before a document is read for the purpose of image correction, a read sensor 1 is used to read in reference white data, and its output is corrected. This is generally called shading and abnormal output appearing when a stain sticks on the read surface side of contact glass 2 or the document pressure side of the white pressure plate 3 is detected to recognize the stain. When a document read operation starts, a set document is detected by a detection sensor, and a CPU starts shading on receiving its detection signal, specifies the stain position, a cleaning method, etc., when judging stain abnormality, and prints information on them out as an abnormality report.