A paper handing apparatus having a plurality of bins, a chuck unit and a stapler unit movable up and down along the bins, and a sorting unit. The sorting unit distributes a number of paper sheets received from a copier or similar image forming apparatus to the bins, while the stapler unit binds an end potion of each of the stacks of paper sheets loaded in the individual bins. The stapler is movable between and lockable at a position for binding a paper stack and a position for supplying staples. The stapler unit is removable from the sorting unit. Doors such as a stapler door are provided on the housing of the apparatus. When a door other than the stapler door is opened when the stapler is performing a stapling operation, the stapling operation is continued until it completes.
