A paper sheet processing apparatus capable of preventing a paper sheet from being drawn out by an unauthorized action. The bill processing device includes: an insertion slot into which a bill is inserted; a bill conveyance mechanism capable of conveying the bill having been inserted from the insertion slot; a bill reader reading the bill conveyed by the bill conveyance mechanism; an authenticity judging mechanism judging an authenticity of the bill read by the bill reader; and a pulse output part driving a motor for controlling conveyance speed of the bill by a motor of the bill conveyance mechanism. The pulse output part controls the conveyance speed by the bill conveyance mechanism after the completion of reading by the bill reader.