Abstract: The present invention relates to a device for detecting and measuring tor transmitted from a prime mover to a rotary machine acting as a load. The device includes a torsion shaft through which the torque is transmitted and as a result it is slightly twisted about its axis. A pair of recording mediums are mounted at spaced locations on the torsion shaft. On each recording medium is permanently recorded a periodic signal. A pair of reading head are used to detect the signal on one of the recording mediums while a single reading head is employed to detect the signal on the other recording medium. The output signals generated by the reading heads are processed by a microcomputer to derive the torque information and the direction of rotation of the torque shaft.