An image forming system includes a processing tray, a detecting unit, a stapling unit, a discharge tray, an instruction unit, and a control unit. Recording material, placed on the processing tray, is detected by the detecting unit. When instructed, the stapling unit can staple the detected recording material. Stapled recording material then is discharged to the discharge tray. The control unit controls switching between a first mode wherein a stapling process is executed and a second mode where the stapling unit executes the stapling process after the detecting unit detects recording material inserted into the processing tray and the execution instruction are received. If an instruction to interrupt a power supply of the image forming system is received in the second mode, the control unit causes recording material inserted into the processing tray to discharge to the discharge tray and then interrupts the power supply without the stapling process executing.

A sheet post-processing apparatus includes a first stapler and a second stapler having different thicknesses of sheets on which a binding process can be performed. A control unit can perform a manual staple mode. If the first stapler is selected as a stapler for performing the binding process in the manual staple mode, the control unit controls the alignment member moving mechanism to move alignment members to a position defining a first insertion position for guiding the sheets to a first placing position. If the second stapler is selected, the control unit controls the alignment member moving mechanism to move the alignment members to a position defining a second insertion position for guiding the sheets to a second placing position.

A sheet post-processing apparatus includes a first stapler and a second stapler having different thicknesses of sheets on which a binding process can be performed. A control unit can perform a manual staple mode. If the first stapler is selected as a stapler for performing the binding process in the manual staple mode, the control unit controls the alignment member moving mechanism to move alignment members to a position defining a first insertion position for guiding the sheets to a first placing position. If the second stapler is selected, the control unit controls the alignment member moving mechanism to move the alignment members to a position defining a second insertion position for guiding the sheets to a second placing position.

An image forming system includes a processing tray, a detecting unit, a stapling unit, a discharge tray, an instruction unit, and a control unit. Recording material, placed on the processing tray, is detected by the detecting unit. When instructed, the stapling unit can staple the detected recording material. Stapled recording material then is discharged to the discharge tray. The control unit controls switching between a first mode wherein a stapling process is executed and a second mode where the stapling unit executes the stapling process after the detecting unit detects recording material inserted into the processing tray and the execution instruction are received. If an instruction to interrupt a power supply of the image forming system is received in the second mode, the control unit causes recording material inserted into the processing tray to discharge to the discharge tray and then interrupts the power supply without the stapling process executing.