Abstract: A motor realizes mechanical field-weakening control by controlling the leakage magnetic flux from the rotor cores of the motor. The motor includes a stator, a rotor including rotor cores circumferentially spaced apart from one another inside the stator and permanent magnets disposed between the respective rotor cores which extend radially from the stator, and a magnetic flux adjustment unit including a ring-shaped main frame, magnetic substance portions extending from the main frame so as to be circumferentially spaced apart from one another and non-magnetic regions defined between the magnetic substance portions. The magnetic flux adjustment unit is rotatable to control the leakage magnetic flux from the rotor cores.