A motor capable of suppressing the torque ripple includes a rotor, a stator and stator coils. The rotor is provided with a plurality of permanent magnets which are arranged at a constant pitch in the circumferential direction. The stator surrounds the rotor and is formed with a plurality of stator poles and a slot located between every two stator poles. The stator coils are wound on the stator and are supplied with three-phase sinusoidal current. The rotor is composed of a plurality of rotor portions which are arranged in the axial direction of the rotor. The difference between the open angle of each permanent magnet of one rotor portion and the open angle of each permanent magnet of another rotor portion is an integral multiple of 30.degree. in electrical angle. When three-phase sinusoidal current is applied to the stator coils, a torque ripple is generated. However, the phase of a torque ripple generated at one of the rotor portions arranged in the axial direction can be made different from the phase(s) of torque ripple(s) generated at other rotor portion(s).