Abstract: A torque detecting system for detecting the torque acting on a rotational member has first and second magnetic heads provided spaced from each other in the axial direction of the rotational member, and a third magnetic head provided spaced from the first magnetic head by a predetermined angle .theta.o in a circumferential direction of the rotational member. First and second magnetic layers are provided on the peripheral of the rotational member and position signals are recorded on the respective magnetic layers through the first and second magnetic heads while the rotational member is rotating under no load. The position signals recorded on the magnetic layers are reproduced through the first to third magnetic heads while the rotational member is rotating under load. The phase difference .DELTA.

Abstract: First and second magnetic layers are respectively fixed in two positions on a peripheral face of a rotary shaft. A magnetizing pattern is preformed at a constant pitch solely on a magnetic face of the first magnetic layer. In a preparatory step, the magnetizing pattern is copied onto a magnetic face of the second magnetic layer, so that a torque detection step is started. In the torque detection step, there is detected phase difference between reproducing signals of two magnetic heads owing to the torsional deformation of the rotary shaft caused by torque. In addition, the number of rotations for a unit time of the rotary shaft is detected based on one of the reproducing signals. Consequently, the applied torque can be obtained by calculation based on the phase difference and the number of rotations for a unit time.