Radial force and tangential force, which deform stator core, are the main causes of vibration and noise. There are many methods to minimize such exciting forces by designing of rotor shape. However, modification of rotor shape increase development cost of the motor. Therefore, step skewed rotor is applied to the design in order to reduce exciting force so that both reduction of vibration and noise and cost-effectiveness of development can be achieved. In order to consider step skewed rotor in interior permanent magnet synchronous motor (IPMSM), 3-dimensional finite element analysis (FEA) is used to consider leakage flux in axial direction and overhang effect. Furthermore, deformation of stator core caused by exciting force is analyzed. Comparison between prototype and step skewed model is made in terms of analysis result of exciting force, deformation of stator and experimental result of vibration to verify the design method.