This paper sheet processing device (10) is provided with: a feed-out unit (16) that feeds out paper sheets one by one that are stored in a storage unit (14), and can alter the feed-out speed; detection units (50, 66, 68) that detect the length in the feed-out direction of the paper sheets and the gap between the paper sheets; and a control unit (60) that controls the feed-out unit (16). On the basis of the length in the feed-out direction of the paper sheets and the gap between the paper sheets detected by the detection units (50, 66, 68), the control unit (60) controls the feed-out unit (16) in a manner so as to alter the feed-out speed of the paper sheets in the feed-out unit (16) each time paper sheets are fed out by the feed-out unit (16).