substituted for attachment to the input and output shafts thus in the above mentioned embodiment the printed wiring board provided with the resistance layer and the electrodes which constitute a potentiometer and the slip rings to take signals from the electrodes to the outside are mounted on either one of the input and output shafts and the slider is mounted on the other one the slider extending in the radial direction to contact with the resistance layer and the output electrode of the printed wiring board accordingly the entire construction of a signal detecting assembly for the steering torque detecting device can be simple and small sized fig4 and 5 show another embodiment of the steering torque detecting device according to the present invention in fig4 and 5 the same reference numerals as in fig1 3 designate the same or corresponding parts and therefore description of these parts is omitted as shown in fig4 a zero point detecting unit 26 is formed at a symmetric position to the potentiometer 15 with respect to an x x line namely the zero point detecting unit 26 is formed in a space remaining unutilized on the surface of the printed wiring board 14 the zero point detecting unit 26 comprises a zero point electrode 26a having a.