A torque sensor includes a magnetism generation portion that rotates together with a first shaft, a rotating magnetic circuit portion that rotates together with a second shaft, a fixed magnetic circuit portion fixed to a housing, a magnetism detector that detects a magnetic flux density guided from the magnetism generation portion to the fixed magnetic circuit portion through the rotating magnetic circuit portion in accordance with torsional deformation of the torsion bar, and a shield disposed between the rotating magnetic circuit portion and the magnetism detector in order to shield the magnetism detector magnetically.