To provide a device for binding paper sheets and a method for binding paper sheets in which some stacked-up paper moneys can be recovered to their flat original states without folding or cutting them after they are bundled.

This invention is comprised of a stacking-up plate 65 for stacking-up some paper moneys P; a deforming means 78 for pressing some stacked-up paper sheets or moneys P stacked up on the stacking-up plate 65 by first to third pressing rollers 68, 69, 70 and a pair of pressing claws 75, 76 from both surfaces in their stacking-up direction so as to cause the stacked-up paper sheets to be deformed in a corrugated shape; and a seal applying segment for winding a paper band (k) around the stacked-up paper sheets deformed by the deforming means 78 for deforming the stacked-up paper sheets into a corrugated shape along the corrugating direction and binding them up.