To provide a post-processing device provided with a shift discharge function capable of shift-discharging without damaging paper even when the paper being carried is long.

This post-processing device is provided with an interference avoiding means to retract a paper bundle to be horizontally moved by a cursor 38 to a position where the paper bundle no longer interferes with a paper discharge part (carrying roller ro6) in accordance with the size of the paper. The interference avoiding means may comprise that to move a second paper receiving part 33 containing the paper bundle for a prescribed quantity in a paper carrying direction before moving the paper bundle to be horizontally moved by a cursor 38 is moved to a prescribed position where it is discharged by the paper discharging part (carrying roller ro6).