1. A paper sheet processing apparatus for performing a recognizing process of a paper sheet, the paper sheet processing apparatus comprising: an image reader that reads an image of a paper sheet; a number-recognition condition memory that stores number recognition conditions for recognizing a number given to the paper sheet; and an image processing unit/character recognizing unit that recognizes a number of the paper sheet from an image read by the image reader, based on the number recognition conditions stored in the number-recognition condition memory.