To provide an eddy current type deceleration unit with a light structure easy to manufacture with high brake performance.

An eddy current type deceleration unit includes a brake drum 15 joined with a rotating shaft, a guide cylinder 6 having an inner hollow part 20 with a rectangular cross section in the control drum 15. The guide cylinder 6 is mounted on a stationary part like a vehicle frame. In addition, a magnet cylinder 9 made up of a magnetic body for joining a plurality of magnets 8 at intervals in the peripheral direction is supported reciprocally in the axial direction in the guide cylinder 6. An outer cylinder part 14 opposite to the inner peripheral face the control drum 15 of the guide cylinder 6 is made of a sheet of a soft magnetic material, and a part 14 for covering a gap between magnets 8 is subjected to plastic deformation.