To enable installation of paper sheets bored and folded in a post- treatment device in a filing hole through part, and to form the through-hole, while aligning position of the holes of a booklet to be manufactured by folding multiple bored paper sheets.

This post-treatment device has a boring means 40 for boring a paper sheet filing hole at the predetermined positions of one paper sheet S carried by a paper sheet S carrying means, and a folding means 80 for folding the paper sheet S at a central part thereof in the carrying direction. The paper sheet carrying means carries the paper sheet S by the predetermined distance, and the boring means 40 bores paper sheet filing holes h1 and h2 at symmetrical positions in relation to a folding line a at the central part in the paper sheet carrying direction as the center line of the folding.