PURPOSE: To prevent conventional noise from being produced, by providing such an arrangement that a pair of gears for transmitting rotary power through the meshing thereof with the use of the Meissner effect are made to be repulsive so that they operate in a contactless condition.

CONSTITUTION: For example, a gear 1 is made of a flat magnet having its magnetic force lines H led between gears 1, 3. The gear 3 is the one serving as a superconductor having a thickness greater than that through which the magnetic force lines H enter so that at least the periphery of the outer surface of the gear 3 with respect to the gear 4 exhibits a complete diamagnetism due to the Meissner effect. Accordingly, when the magnetic force lines H of the gear 3 are concentrated between the gears 1, 3, a repulsive force in proportion to the square of the strength of the magnetic field is effected between the gears 1, 3. Accordingly, by setting the repulsive force of the magnetic field H to be greater than the drive force of the gears, the gears 1, 3 transmit power in a mechanically contactless condition. Incidentally, if a cover 7 attached to the gear 1 is made of a superconductor, the magnetic force may be effectively introduced between the gears 1, 3 due to the characteristic of complete diamagnetism.