A stapler includes a staple cartridge in which a staple is stored, a storage unit to which the staple cartridge is attached to be detachable, a staple ejecting unit which ejects out the staple to penetrate a 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 that is 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. The cut staple storage unit is attachable to and detachable from the stapler.

A stapler includes 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 a paper sheet, a cutting unit which cuts a staple leg of the staple penetrating the paper sheet, a binding unit which bends the staple leg of the staple penetrating the paper sheet to bind the paper sheet, a cut staple storage unit which stores a cut staple that is cut by the cutting unit, a cut staple quantity detection unit which detects a quantity of the cut staple stored in the cut staple storage 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. The cut staple storage unit is attachable to and detachable from the stapler.

A binding device includes a sheet-bundle forming unit; a binding unit that executes a series of operation including inserting a wire into a sheet bundle and bending the wire; a power supply unit; a detector that detects a first timing for transitioning from bending operation to recovery operation; a first timekeeper that measures time from a start point of the series of operation to a first time point, which is an end of a scheduled first-timing detection period; a unit-of-processing manager; and a supply power controller. When the first time point is reached before detection of the first timing, the controller causes the power supply unit to adjust the electric power before the first timing is reached, such that the first timing is detected before the first time point in the series of operation for a second bundle belonging to the same unit of processing as a first bundle.

A binding device includes a sheet-bundle forming unit; a binding unit that executes a series of operation including inserting a wire into a sheet bundle and bending the wire; a power supply unit; a detector that detects a first timing for transitioning from bending operation to recovery operation; a first timekeeper that measures time from a start point of the series of operation to a first time point, which is an end of a scheduled first-timing detection period; a unit-of-processing manager; and a supply power controller. When the first time point is reached before detection of the first timing, the controller causes the power supply unit to adjust the electric power before the first timing is reached, such that the first timing is detected before the first time point in the series of operation for a second bundle belonging to the same unit of processing as a first bundle.

An image forming system including an image forming apparatus configured to form an image on a sheet, a post-processing apparatus comprising a binding device configured to bind the sheet output from the image forming apparatus, and a control unit configured to control the binding device. The binding device is capable of executing binding processing via a staple forming process of forming a staple and moving the staple toward a striking-out position and a staple striking-out process of striking out the staple at the striking-out position. The control unit is configured to control the binding device to repeat multiple times the staple forming process without undergoing the staple striking-out process.