Provided is a paper sheet processing apparatus capable of distinguishing a counterfeit bill or a paper sheet suspicious to be a counterfeit bill from bills inserted through an insertion slot to stop a wrongdoing. A storage unit stores information on a paper sheet read by a bill reader and a verification unit verifies the paper sheet using the information on the paper sheet stored in the storage unit. If the paper sheet is determined to be counterfeit in the verification, a conveyance unit conveys the paper sheet toward the insertion slot. A comparison unit compares the image data of the inserted paper sheet with image data of a previously inserted paper sheet and if the image data of the inserted paper sheet is determined to be identical to the image data of the previously inserted paper sheet in the comparison, a control unit sends a signal to a host apparatus.