Abstract: A copier with an automatic document feeder (ADF) selectively feeds a document to a predetermined position on a glass platen by the ADF at two different timings: a first timing for feeding a paper sheet after confirming that the document has not been misfed and a second timing for feeding a paper sheet immediately without determining whether or not the document has been misfed. A paper sheet associated with the first document is fed at the first timing while paper sheets associated with the second and successive documents are fed at the second timing. A paper sheet which has undergone a copying operation once and which is on an intermediate tray of the copier is refed from the tray at the first timing for another copying operation. When the document is misfed, predetermined processing is executed by determining that a paper sheet associated with that document is unavailable.