An apparatus for processing paper sheets, in which one lot of paper sheets are set in a supplying section and supplied one after another to a detecting section for sorting these paper sheets into fit paper sheets and unfit paper sheets. The unfit paper sheets collected are manually counted by the operator, and their number is inputted as key-in-data. The inputted number of unfit paper sheets is added to the automatically counted number of fit paper sheets, and the resultant sum is checked up with a preset paper sheet number of one lot. The processed fit paper sheets are received in a temporary collecting section until completion of the checkup of the paper sheet number of one lot.