This paper presents results from radial force and stator radial vibration calculations using the 3D finite element method. Because of the special construction of a hybrid stepping motor with both unipolar flux due to the rotor magnet and heteropolar fluxes due to the currents in stator poles it is treated as a 3D magnetostatics problem. The radial force in the air gap under each stator pole has been calculated by the Maxwell stress method. The variation of radial force under each pole with one rotor tooth pitch movement is analyzed by Fourier series to obtain the force frequency spectrum with magnitudes and phase angles. It is then multiplied by the corresponding measured stator mobility values to obtain the stator radial vibration. The results are compared with experimental data and have shown a reasonable agreement.