A sheet processing apparatus that forms asperity on a sheet bundle so as to bind the sheet bundle, has a pair of rotating members having a concave and convex portions on the outer periphery, a moving portion that moves at least one of the pair of the rotating members so as to nip the sheet bundle by the pair of the rotating members or release the sheet bundle, and a controlling portion that controls the moving portion to allow the pair of rotating members to rotate with a concave portion of one rotating member and a convex portion of the other meshed with each other while nipping the sheet bundle or releasing the sheet bundle.