Electric power steering is designed to use an electric motor to reduce effort by providing steering assist to the driver of a vehicle. EPS have advantages which are economical and eco-friendly compare with hydraulic power steering, because power steering oil is not used and efficiency of vehicle is increased to 3-5 %. Since EPS is connected to handle of vehicle, noise and vibration have an effect on the driver directly. So study on the reduction of noise of vibration of EPS is proceeding. This paper deals with reduction of noise and vibration which are generated by electrical forces between stator and rotor according to reduction of permanent magnet. In order to analyze noise of surface permanent magnet (SPM) motor, this paper deals with relation between deformation of stator and noise from motor. The normal and tangential force which affects on the tooth are computed by equivalent magnetizing current (EMC).