Sheet processing apparatus and image forming apparatus

A sheet processing apparatus, comprising:

• a binding unit including:
• a stapler configured to staple a bundle of sheets by driving a staple into the sheet bundle;
• a cutting mechanism configured to cut-off end portions of the staples driven into the sheet bundle;
• a storage portion which stores cut-off end portions of staples;
• a lid mounted on the storage portion capable of opening and closing;
• an open and closed state detecting portion configured to detect an open and closed state of the lid;
• a collecting portion configured to collect cut-off end portions of staples from the storage portion;
• and
• a lid opening and closing portion configured to open the lid when the cut-off end portions of staples are collected from the storage portion to the collecting portion,
• wherein after the lid opening and closing portion has performed a lid opening and closing operation of a lid opening motion and then a lid closing motion, if the open and closed state detecting portion detects that the lid is not closed, the lid opening and closing portion repeats the lid opening and closing operation.