Eddy-current-type reduction gear

A single-row rotating-type eddy-current-type reduction gear, wherein the number of components is not large, and low cost is achieved and the amount of operating power needed during switching between braking on and braking off is reduced while further reduction in the size of the device is achieved. A magnet support member (4) for a ferromagnetic material in which permanent magnets (3) are arranged with a constant interval therebetween is provided facing a braking drum (2) so as to be able to rotate through a necessary angle, so that magnetic poles are in opposite orientations to each other in the circumferential direction of the braking drum (2), which is attached to a rotating shaft (1). A support (3) in which a group of pole pieces (5) of a ferromagnetic material arranged at basically the same angle positions as the permanent magnets (3) is provided with support members (6a) of a non-magnetic material interposed between the pole pieces (5) is provided between the group of permanent magnets and the braking d