Binding apparatus and image forming system including same

A binding apparatus configured to bind a sheet bundle, the binding apparatus comprising:

• a pair of pressing members configured to sandwich and press the sheet bundle to bind the sheet bundle;
• a rotator configured to rotate to periodically cause the pair of pressing members to separate and contact with each other;
• a detector configured to detect whether the rotator is between a first position at which the pair of pressing members is separated from each other and a second position downstream from the first position in a forward rotation direction of the rotator, the second position upstream in the forward rotation direction from a peak position at which a pressing force between the pair of pressing members is maximum;
• and
• control circuitry configured to rotate the rotator in a reverse direction to the forward rotation direction to move the rotator to the first position in response to a detection, by the detector, that the rotator is between the first position and the second position in the forward rotation direction.