Abstract: A mobile telephone fastening with vibration function includes a cramp and a body combined by a casing and a cover. The cramp is adhered to a back of the mobile telephone and has a projection formed on a rear face to be engaged with the body. The body has a printed circuit board, a battery, and a motor with an eccentric wheel respectively received in appropriate cavities defined by the casing and the cover. When a telephone call is received by the mobile telephone, the printed circuit board receives the signal and drives the motor to operate, which in turn rotate the eccentric wheel to produce a vibration to inform the user of the incoming telephone call.