Patent ID: 8020454

Claim:
A torque detection device comprising: a set of magnetic flux collecting rings, arranged outside an outer periphery of a magnetic circuit forming member provided in a rotating body applied with a torque, for collecting a magnetic flux generated by the magnetic circuit forming member; a detector for detecting the torque applied to the rotating body based on a density of the magnetic flux collected by the set of magnetic flux collecting rings; and a holding ring for holding the set of magnetic flux collecting rings and the detector and including, on an outer periphery, an attachment part to be attached to a stationary object having a collar part, wherein the holding ring includes, on one end face in an axis line direction thereof, an attachment-preventing convex part for preventing attachment to the stationary object by contacting the stationary object, and wherein the attachment-preventing convex part contacts the collar part of the stationary object when the holding ring is attached to the stationary object in a direction opposite to an appropriate direction, and the attachment-preventing convex part does not contact the collar part of the stationary object when the holding ring is attached to the stationary object in the appropriate direction.