PURPOSE: To make a motor torque higher by using a superconducting material for either a stator or a rotor.

CONSTITUTION: In a motor, triangular protrusions are periodically formed on the circumference 5a of a rotor 5 composed of a superconducting material. First∼third armature windings 6 are provided in positions where the periods and phases of said protrusions on said circumference 5a are respectively different by one thirds. A diamagnetic current flowing in the direction of cancelling a magnetic field and being a permanent current is generated in the rotor 5 composed of superconducting material by an electric field produced by said armature windings 6. Said diamagnetic current is taken out as a torque according to the density distribution of the magnetic field and magnetic flux generated at that time by the armature winding 6 and superconducting material.