A sheet processing apparatus includes first and second sheet processing modules, a connecting module, and a storage module. In each of the first and second sheet processing modules, a sheet received from an entrance port is identified by an identifying unit, and if the sheet is qualified, the sheet is transported to a first communication port through a first transport path. In the connecting module, a first diverter mechanism is configured to permit sheet transport between a second communication port and a selected one of the first and second sheet processing modules. The storage module is disposed for receiving and storing the sheet from the connecting module.