When a jam is detected in a post-processing device, a purge controller first makes a conveyance roller group and a reverse roller continue conveyance. The purge controller then sets the conveyance destination of a leading sheet that will first arrive at a branch point after the time of detection of the jam. When a first condition is satisfied the purge controller sets the conveyance destination to a reverse slot, and when a second condition is satisfied the purge controller sets the conveyance destination to an outlet path. The first condition is satisfied when no other sheet is present in the reverse slot at the time of detection of the jam, and the second condition is satisfied when another sheet is present in the reverse slot at the time of detection of the jam.