IPMSM for traction motor has high power density and wide operating range. But high power density causes internal temperature rise and it makes big armature reaction which causes irreversible demagnetization. And with wide operating range, rotor rotating fast gets stress from centrifugal force. For this reason, traction motor is designed to considerate stress of rotor and irreversible demagnetization for reliability. This paper explains shape design method of 120kW IPMSM accounting improvement of reliability. Finally, the validity of the analysis and the performance evaluation were verified through testing of the final model.