PROBLEM TO BE SOLVED: To provide an eddy current decelerating device using a permanent magnet, which is compact, does not need large power and can be used even if a trouble occurs in the feeder system to a rolling stock.
SOLUTION: A disk 12 is fitted to an shaft 1 via a boss 11. Bearing units 16a and 16b are fitted to the axle 1 by sandwiching the boss 11. A semicircular stator assembly 17 is detachably fitted to the bearing units 16a and 16b to surround a part of the disk 12. The stator assembly 17 is provided with pole pieces 17a, which are fixed and arranged on the same circumference on both sides sandwiching the disk 12 by leaving a prescribed interval, inner permanent magnet strings 17b, where N poles and S poles are alternately fixed and arranged at positions facing the inner peripheral parts of the pole pieces 17a on the facing side of the disk 12, outer permanent magnet series 17c, where the N poles and the S poles are alternately arranged in positions facing the outer peripheral parts of the pole pieces 17a, so that one pitch of the pole pieces 17a can be rotated and a hydraulic cylinder 17k which causes the outer permanent magnet strings 17c to turn. A copper layer 20 is installed on a surface facing the pole pieces 17a of the disk 12.