To prevent generation of a large collision sound, even if paper is continuously fed, by folding the paper without allowing the paper to abut on a stopper.

This paper folder includes first and second folding rollers 16 and 17 separately rotatably journaled by a roller plate 15 coaxially rockably arranged with a main roller 14 and rotating by coming into pressure contact with the main roller, and first and second feed rollers 18 and 19 rotatably journaled by coming into pressure contact with each other, and is controlled so that when holding the roller plate in a first rocking position, the first folding roller 16 separates from the first feed roller 18, and the second folding roller 17 comes into pressure contact with the second feed roller 19, and when holding the roller plate in a second rocking position, the second folding roller inversely separates from the second feed roller, and the first folding roller comes into pressure contact with the first feed roller.