Stapler, post-processing apparatus and image forming system

A post-processing apparatus comprising a stapler, the post-processing apparatus performing post-processing on a paper sheet on which an image is formed, the stapler including:

• a staple cartridge in which a staple is stored;
• a storage unit to which the staple cartridge is detachably attached;
• a staple ejecting unit which ejects the staple to penetrate the paper sheet;
• a cutting unit which cuts a staple leg of the staple penetrating the paper sheet;
• a binding unit which binds the paper sheet by bending the staple leg of the staple penetrating the paper sheet;
• a cut staple storage unit which stores a cut staple cut by the cutting unit;
• and
• a discharge unit through which the cutting unit and the cut staple storage unit communicate with each other to guide the cut staple to the cut staple storage unit,
• wherein the cut staple storage unit is detachable from the stapler.