To provide a paper sheet processing device capable of enhancing processing efficiency and reducing working load by an operator.

A bank note processing device 1 has a feeding part 2 for feeding a plurality of sheets of bank notes, a taking-out part 3 for taking out the fed bank note on a carrying passage 4, a thickness inspecting part 6 for inspecting thickness of the taken out bank note, a separation carrying passage 8 for leading the plural sheets of bank notes judged as overlapping taking as a result of the inspection, and a temporary accumulating part 10 for temporarily accumulating the plurality of sheets of bank notes led via the separation carrying passage 8. The plurality of sheets of overlappedly taken bank notes passing through the separation carrying passage 8 are dealt and separated and are accumulated in the temporary accumulating part 10. The accumulated bank notes are fed out on the carrying passage 4 at feeding out speed slower than carrying speed.