To provide a paper sheet processor for performing batch processing capable of using a dummy card as a batch card by exchanging the batch card for the dummy card when paper sheets are erroneously detected by the batch card.

A batch card detection device 8 is provided with a color sensor, and a color to be detected by the color sensor is set (S1). Then, the detection pattern color of the batch card is set (S2). Then, payment processing by a paper sheet processor is executed (S3). When the erroneous detection of the batch card is not present in the payment processing (S3; No), the process returns to a step S1, and the next batch processing is executed. On the other hand, when the erroneous detection of the batch card is frequent (S4; Yes), an operator performs the processing of changing the batch card. At first, the detection color of the batch card is matched with the detection color of the dummy card (S5). Then, the color of the detection pattern of the batch card is matched with the detection color of the dummy card.