TORQUE SENSOR

PROBLEM TO BE SOLVED: To reduce an excitating current without degrading sensor quality and increasing circuit size. SOLUTION: A first and a second magnetic anisotropic parts are so formed on the outer peripheral surface of a torque transfer shaft that one side is compressed and the other side is pulled when torque is loaded to the torque transfer shaft. On the outer peripheral sides of the magnetic anisotropic parts, a first and a second detection coils 4b, 5b, and a first and a second excitating coils 4a, 5b which are connected in series and excite the detection coils 4b, 5b when a sine wave AC voltage having a specified frequency is applied from a high frequency power source 8 are arranged, in such a manner that changes of permeability of the magnetic anisotropic parts are converted to voltage changes of one ends of both the detection coils 4b, 5b. A magnetostriction type torque sensor forms a signal voltage showing the direction and magnitude of a torque, from the difference of voltages of the one ends of both the detection coils. A capacitor 13 is connected in parallel with the first and the second exiting coils 4a, 5a, and a parallel resonance circuit is constituted.