When reading of the documents set on the document feed tray is given priority by user designation, the documents set on the document feed tray are read first, then the document set on the platen plate is read. When reading of the document set on the platen plate is given priority, the document set on the platen plate is read first, then the documents set on the document feed tray are read. Even when originals are composed of documents that can be set on the document feed tray and an original that cannot be set on the document feed tray, use of the above configuration makes it possible to achieve copying of the originals as one job.