An electric rotating machine (1D - 1G) comprising: a rotatable rotor having first magnetic field parts and second magnetic field parts formed in an inner peripheral surface and an outer peripheral surface of a circular tube part, respectively, by arranging permanent magnets (3a, 3b) in a circumferential direction; a first stator equipped with coils opposing, in the radial direction, the first magnetic field parts disposed in the outer peripheral surface of the rotor, the coils forming first stator magnetic fields (α); a second stator equipped with coils opposing, in the radial direction, the second magnetic field parts disposed in the inner peripheral surface of the rotor, the coils forming second stator magnetic fields (β); and a case for fixing the first stator and the second stator and surrounding the rotor, the electric rotating machine further comprising a controller having a power feeder for driving the rotor to rotate by supplying power to coils (6a, 6b) of one of the first stator and the second stator, and a power collector for extracting an induced current generated in the coils (6a, 6b) of the other stator (7a, 7b) resulting from rotation of the driven rotor, characterized in that at least the coils (6a, 6b) of the stator (7a, 7b) disposed on the power supply side are formed by a superconducting material, a current supplied to the superconducting coils (6a, 6b) being made larger than an induced current generated in the coils (6a, 6b) of the other stator ( 7a, 7b); and the rotor is capable of rotating in a levitated state and formed into a cylindrical body, wherein the circular tube part has the first magnetic field parts and the second magnetic field parts and wherein both axial ends of the circular tube part are free, and between the coils of the first stator and the coils of the second stator and permanent magnets (3a, 3b) of the rotor, magnetic forces serving as magnetic gap forming means adapted to form a radial gap by causing the rotor to levitate due to magnetism are provided, and magnetic forces serving as magnetic position setting means adapted to optimize an axially relative position of the levitated rotor are provided, wherein the rotor is levitated by the magnetic force received from the stator set to the motor mode. a rotatable rotor having first magnetic field parts and second magnetic field parts formed in an inner peripheral surface and an outer peripheral surface of a circular tube part, respectively, by arranging permanent magnets (3a, 3b) in a circumferential direction; a first stator equipped with coils opposing, in the radial direction, the first magnetic field parts disposed in the outer peripheral surface of the rotor, the coils forming first stator magnetic fields (α); a second stator equipped with coils opposing, in the radial direction, the second magnetic field parts disposed in the inner peripheral surface of the rotor, the coils forming second stator magnetic fields (β); and a case for fixing the first stator and the second stator and surrounding the rotor, the electric rotating machine further comprising a controller having a power feeder for driving the rotor to rotate by supplying power to coils (6a, 6b) of one of the first stator and the second stator, and a power collector for extracting an induced current generated in the coils (6a, 6b) of the other stator (7a, 7b) resulting from rotation of the driven rotor, characterized in that at least the coils (6a, 6b) of the stator (7a, 7b) disposed on the power supply side are formed by a superconducting material, a current supplied to the superconducting coils (6a, 6b) being made larger than an induced current generated in the coils (6a, 6b) of the other stator ( 7a, 7b); and the rotor is capable of rotating in a levitated state and formed into a cylindrical body, wherein the circular tube part has the first magnetic field parts and the second magnetic field parts and wherein both axial ends of the circular tube part are free, and between the coils of the first stator and the coils of the second stator and permanent magnets (3a, 3b) of the rotor, magnetic forces serving as magnetic gap forming means adapted to form a radial gap by causing the rotor to levitate due to magnetism are provided, and magnetic forces serving as magnetic position setting means adapted to optimize an axially relative position of the levitated rotor are provided, wherein the rotor is levitated by the magnetic force received from the stator set to the motor mode.