To increase the operating rate of a device by reducing jamming caused by an error in sorting paper sheets, and reducing workload necessary for correcting jamming.

This paper sheet processing device 1 involves a main conveyance path 3 for conveying a plurality of paper sheets taken continuously from a taking-out device 4. The first to third gates 11, 12, 13 switching the conveyance direction of the paper sheets are disposed sequentially on the main conveyance path 3, a pitch sensor 20 detecting the short pitch of the paper sheets is disposed on the upstream side from a shift sensor 18e just before the first gate 11 with a prescribed distance spaced. When the preceding paper sheet of two paper sheets continuously conveyed is detected by the shift sensor 18e and the subsequent paper sheet is on the pitch sensor 20, the short pitch is determined and two paper sheets are rejected to a rejected-ticket accumulating device 14.