PURPOSE: To obtain a rotational driving source without exhaust gas and noise, by arranging superconducting units to be confronted with a rotor having a magnet, and by permitting cooling fluid to flow to the superconducting units periodically to change the temperature of the superconducting units periodically.

CONSTITUTION: Superconducting units 1a∼1c are arranged on a cylinder 2 and are set to be stators, and a rotary body 4 provided with a magnet 3 to be confronted with the stators is rotatably supported by a shaft 6. To the superconducting units 1a∼1c, cooling gas is periodically fed via a space 5. On the superconducting units 1a∼1c, Meissner effect is periodically worked, and between the units and the magnet 3, periodic repulsion is generated, and the rotary body 4 is contrived to be rotationally driven in one direction. As a result, a new rotational driving source without the generation of exhaust gas and noise unlike an internal combustion engine can be obtained.