To provide a paper treatment device being stably operated by preventing inconvenience at a paper delivery part caused by the difference of a staple mode.

Although there is the difference in the maximum number of sheets of papers to be treated in one staple treatment according to paper size, paper thickness and paper kind, the maximum number of sheets is also different depending on the staple mode. Here, the maximum number of sheets in the staple treatment is changed according to the staple mode, and paper delivery jam that the paper subjected to staple treatment is jammed at the paper delivery part and inconvenience that the papers are delivered to a paper delivery tray at the irregular state or the like are prevented.