A torque sensor for use in detecting torsion of a power steering device or the like of a vehicle. The torque sensor is provided with a first shaft supported for rotation about its axis in a casing, a permanent magnet secured to the first shaft, a second shaft supported for rotation about its axis in the casing and disposed in end-to-end relationship to the first shaft, a connecting shaft for connecting the first shaft and the second shaft, a magnetic core secured to the second shaft and a magnetism sensor secured to the casing and sandwiched between ring-shaped magnetic members disposed in the vicinity of the outer peripheral face of the magnetic core so that a change in magnetic flux which is caused by the relative displacement of the permanent magnet and the magnetic core is detected by the magnetism sensor as the direction of a variation in the relative position of and the amount of variation in a displacement of the first shaft and the second shaft about the axis of rotation of the first and second shafts.