Permanent magnet synchronous (PM) motors are widely used for industrial applications. In the PM motor drives, it is difficult to achieve the wide speed and constant power operations, which are desired in traction and spindle drives, because the field-flux of PM motor is uncontrollable and as a result the field-weakening control is not available. The air-gap flux, however, can be weakened by the demagnetizing effects due to the d-axis armature reaction (flux-weakening control). In this paper, the wide speed control method of the interior PM (IPM) motor, which includes the maximum torque-per-ampere control and the flux-weakening control, is proposed. In the high-speed flux-weakening region, there are some cases where the control performances become worse and the control system becomes unstable because of the saturation of current regulator and the effects of magnetic saturation. The high performance current regulator compensating these effects is also proposed. The control performances of the proposed control system are confirmed by the several drive tests with respect to the prototype IPM motor.