A cage nut includes a substantially rectangular base portion, two sidewalls, two stopper portions, two arm portions, two clamping portions, and a nut. The sidewalls extend from two opposite edges of the base portion. Each stopper portion extends from an end of a corresponding sidewall away from the base portion. The two stopper portions extend toward each other. Each arm portion extends outwardly from an end of a corresponding stopper portion. Each clamping portion extends from an end of a corresponding arm portion and includes a first side edge and a second side edge. The first side edge and the second side edge are arranged in an angle. The angle is equal to or less than about degrees. The clamping portions extend away from each other. The base portion, the two sidewalls and the two stopper portions define a receiving space. The nut is received in the receiving space.