PURPOSE: To make non-contact braking of a rotor possible by controlling the quantity of magnetic flux of a permanent magnet which enters a superconductor, and by applying proper revolution resisting force to the rotor.

CONSTITUTION: When a superconductor 5 is arranged being separated from a permanent magnet 2 fitted to a rotation axis 1, magnetic flux emitted from the permanent magnet 2 exerts no influence on the superconductor 3, and when the rotation axis 1 is rotated it rotates without rotation resistance. If the superconductor 3 is made to approach the permanent magnet 2 under this condition, a part of the magnetic flux emitted from the permanent magnet 2 enters the inside of the superconductor 3. In the case of a permanent magnet 2 whose magnetic field strength distribution is not uniform by the rotation of the rotation axis 1, under this condition, magnetic field strength which the superconductor 3 receives is always changed. Accordingly, the distribution of the magnetic flux entering the superconductor 3 becomes nonuniform to the center of the rotation axis. In the end, the entering magnetic flux becomes resistance which prevents rotation of the rotation axis 1 and makes the rotor 1 stop gradually. And this makes non-contact braking of the rotor possible.