Torque measuring apparatus for rotating body

A torque measuring apparatus of the present invention comprises a rotor having a hollow body portion formed between a drive-side flange portion and a load-side flange portion; light emitting elements disposed on a periphery of the rotor, for emitting optical signals based on an output from a torque detection unit attached to a hollow portion of the hollow body portion; a transparent plate attached to a chassis disposed outside the rotor, for allowing the optical signals to pass therethrough; and a signal receiving unit arranged on the chassis, for receiving the optical signals via the transparent plate, wherein the transparent plate is detachable from the chassis.