In an image forming apparatus: a report reading portion reads image data of a print report that has already been printed; a memory stores report data of a current time point; a format determining portion determines whether or not the read print report and the report data match in format; a change search portion, when the print report and the report data match in format, determines whether or not changed information is included in the report data by comparing the report data with the print report for each item, the changed information being information that has been changed from corresponding information in the print report; and a change output portion, when the changed information is included in the report data, re-prints the changed information in a vicinity of pre-change information on the print report, the pre-change information corresponding to the changed information.