Abstract: If a being conveyed on which the image of a preceding document of a specific document is formed is jammed on the way including the post-processing device for post-processing while a new paper is fed from a paper feeder for the specific document and being sent into the intermediate tray by conveyer,the controller stops the conveyance of the jamming paper by the conveyer, and allows the paper being towards the intermediate tray to be conveyed to the intermediate tray and stocked, while stopping feed of new paper by paper feeder, and when jamming is cleared, the paper stocked in the intermediate tray is discharged outsides.