To prevent static electricity in cutting wastes without excessively humidifying a sheet.

A sheet processing apparatus 20 includes: a punching unit 40 which cuts off part of a sheet P as a processing object conveyed along a conveying route; and a humidifying unit 30 located on this conveying route in the upstream side of the punching unit 40 and configured to humidify a predetermined area which is selected from the entire area of the sheet P and includes punch areas to be cut off from the conveyed sheet by the punching unit 40.