This paper treats the optimization of rotor construction in the permanent magnet synchronous motor (PMSM) for electric vehicle (EV). While the field system of PMSM has generally one magnet per pole, we replace the magnet into plural sub-magnets. The dimensions of each sub-magnet are determined by the concept of pulse width modulation (PWM). By adopting the proposed rotor construction, we can not only reduce the space harmonics of the air-gap field but also provide space for rotor bars (i.e., damper windings) around the direct-axis. From the investigation by hybrid EE-BE (coupled finite element and boundary element) method coupled with both electric circuit and motion equation, we verify that the construction is effective for practical use.