Paper post-processing apparatus and paper post-processing method

A post-processing method for binding fed paper, including:

• dividing the number of paper subjected to binding process into a plurality of groups;
• feeding a paper to a first processing tray;
• creating a first paper bundle by binding papers for one group on the first processing tray into one bundle every time papers for one group are fed to the first processing tray;
• conveying the first paper bundle from the first processing tray to a second processing tray every time the first paper bundle is created;
• carrying out gluing processing at the upmost paper of the first paper bundle every time the first paper bundle is conveyed to the second processing tray from the first paper bundle of the first group to the first paper bundle of the second to the last group;
• and
• creating a second bundle by pressing the first paper bundles on the second processing tray to glue bind the first paper bundles after conveying the first paper bundle of the last group from the first processing tray onto the first paper bundles on the second processing tray.