To provide an eddy-current reduction gear with which flux leakage into a rotor is prevented at non-braking time.

The eddy-current reduction gear includes a plurality of switch plates 12 made of a ferromagnetic material, placed opposite to the inner circumferential surface of the rotor 10 coupled with a rotating shaft and positioned in the axial direction; intermediate members 13 placed between the switch plates 12 and made of a non-magnetic material; and a plurality of magnets 17 that are placed in the axial direction opposite to the inner circumferential side of the switch plates 12 and are moved to positions which fully faces opposite to the switch plates 12 at braking time and removed from the positions at non-braking time. At non-braking time, at least one of the magnets 17 is so positioned as to straddle one of the intermediate member 13, and one or both of the switch plates 12, adjoining the intermediate member 13 straddled by the magnet 17 at non-braking time, are provided with a protruded portion 22 that is protruded into the intermediate member 13.