An image forming apparatus comprising: an image forming section to form a toner image based on print data; a transfer section to transfer the toner image onto a transfer sheet; a fixing section to fix the toner image transferred onto the transfer sheet; a cleaning section for cleaning at least one of the image forming section, the transfer section and the fixing section; and a control section to determine an existence area of a real image in a print image based on the print data, to determine a size of the transfer sheet, onto which the print image is printed and to control the cleaning device based on determinations of the image determination section and the transfer sheet size determination section.