A method of controlling a motor (12, 12A, 12B, 12C, 12D, 12E), the method comprising: performing, at the motor including: a stator, a first independently rotatable rotor and a second independently rotatable rotor disposed around the stator, a plurality of shifting magnets disposed in one of the first rotor or the second rotor, the plurality of shifting magnets including magnetic poles capable of being reversed by a magnetizing current, and a number-of-magnetic-poles shifter comprising a plurality of teeth disposed at the stator having coils wound therearound and configured to receive the magnetizing current, reverse the magnetic poles of the shifting magnets, a magnetizing operation one time based on determining the position of the first or second rotors (30, 20), and reversing polarities of the shifting magnets when a mode of the motor is shifted from a synchronous mode in which the first rotor and the second rotor rotate in the same direction to a counter mode in which the first rotor and the second rotor rotate in opposite directions; and shifting the mode of the motor to the counter mode while the magnetizing operation is performed one or more times and relative positions of the first rotor and the second rotor are changed when the first rotor and the second rotor inertially rotate in the synchronous mode, wherein the magnetizing operation performed one or more times includes repeating a partial magnetization process, in which the magnetizing current is supplied to a portion of the plurality of shifting magnets; wherein the partial magnetization process includes a short magnetization process in which a length of time during which the magnetizing current is supplied is short, and characterized in that: wherein the short magnetization process is repeatedly performed when the number of simultaneous rotations of the rotor corresponding to magnetization, which is subject to the magnetizing operation, of the first rotor and the second rotor is equal to or less than a predetermined number of rotations, a plurality of fixing magnets disposed in the one of the first or second rotors (30, 20) in which the plurality of shifting magnets are not disposed, and whose magnetic poles are not reversed by the magnetizing current, the number-of-magnetic-poles shifter is configured to shift the number of magnetic poles of one of the first rotor or the second rotor between N and 2N, wherein N is a natural number equal to or greater than 2. performing, at the motor including: a stator, a first independently rotatable rotor and a second independently rotatable rotor disposed around the stator, a plurality of shifting magnets disposed in one of the first rotor or the second rotor, the plurality of shifting magnets including magnetic poles capable of being reversed by a magnetizing current, and a number-of-magnetic-poles shifter comprising a plurality of teeth disposed at the stator having coils wound therearound and configured to receive the magnetizing current, reverse the magnetic poles of the shifting magnets, a stator, a first independently rotatable rotor and a second independently rotatable rotor disposed around the stator, a plurality of shifting magnets disposed in one of the first rotor or the second rotor, the plurality of shifting magnets including magnetic poles capable of being reversed by a magnetizing current, and a number-of-magnetic-poles shifter comprising a plurality of teeth disposed at the stator having coils wound therearound and configured to receive the magnetizing current, reverse the magnetic poles of the shifting magnets, a magnetizing operation one time based on determining the position of the first or second rotors (30, 20), and reversing polarities of the shifting magnets when a mode of the motor is shifted from a synchronous mode in which the first rotor and the second rotor rotate in the same direction to a counter mode in which the first rotor and the second rotor rotate in opposite directions; and shifting the mode of the motor to the counter mode while the magnetizing operation is performed one or more times and relative positions of the first rotor and the second rotor are changed when the first rotor and the second rotor inertially rotate in the synchronous mode, wherein the magnetizing operation performed one or more times includes repeating a partial magnetization process, in which the magnetizing current is supplied to a portion of the plurality of shifting magnets; wherein the partial magnetization process includes a short magnetization process in which a length of time during which the magnetizing current is supplied is short, and characterized in that: wherein the short magnetization process is repeatedly performed when the number of simultaneous rotations of the rotor corresponding to magnetization, which is subject to the magnetizing operation, of the first rotor and the second rotor is equal to or less than a predetermined number of rotations, a plurality of fixing magnets disposed in the one of the first or second rotors (30, 20) in which the plurality of shifting magnets are not disposed, and whose magnetic poles are not reversed by the magnetizing current, the number-of-magnetic-poles shifter is configured to shift the number of magnetic poles of one of the first rotor or the second rotor between N and 2N, wherein N is a natural number equal to or greater than 2.