To suppress the enlargement of a device constitution, and to improve the consistency of a recording material bundle.

This post-processing device comprises: a stacker 21 which is arranged in a state of being inclined and placed with the recording material bundle thereon; a stopper 22 located at the lower end D of the stacker 21; and an air blowing part 3 arranged at the side of the lower end of the stacker 21. A paper sheet bundle S is conveyed into the stacker 21 via a conveyance passage a. The air blowing part 3 blows air to the side of the upper end U from the side of the lower end D of the stacker 21 toward the lower end SD of a recording material which slides down on the placing face P of the stacker 21 toward the side of the lower end D from the side of the upper end U of the stacker 21.