A paper handling apparatus for use with a copier, printer or similar equipment for sorting a number of paper sheets sequentially driven out of the equipment to prepare paper stacks and binding the paper stacks. The apparatus has a plurality of bins, a sorter for sequentially distributing the paper sheets to the individual bins, a mechanism for positioning the paper sheets distributed to the bins, and a stapler for stapling the paper sheets positioned on the bins. The sorter and the stapler are operable simultaneously with each other. The stapler acts on only those bins which are loaded with paper sheets associated with the last document without exception, while not acting on those bins which are loaded with paper sheets associated with the last document but are loaded with only a single paper sheet. The bin on which the stapler is to act is located at least two bins above the bin where the paper sheets are to be positioned. When a timing at which a paper positioning operation should not be executed is detected, priority is given to a stapling operation with the paper positioning operation being inhibited. Whether or not the bin of interest has undergone paper positioning is determined and, based on the result of decision, which of the paper positioning operation and the stapling operation should be executed is determined. The stapling operation is allowed to occur only at the bins where paper sheets have already been positioned.