Torque transmitted via a drive shaft of a motor is contactlessly determined using organic magnetoresistive semiconductor element, unlike known torque sensors that can generate greatly fluctuating measurement signals even at a constant torque. The organic magnetoresistive semiconductor element is mounted on a drive shaft or a coupling thereof. For this purpose, a field generator is provided, which is rigidly connected to the drive shaft or the clutch and which in the environment of the drive shaft generates a magnetic field that is dependent upon the torque. In the environment, the OMR semiconductor element is arranged to be stationary. The OMR semiconductor element has two electrodes between which a voltage source generates an electrical voltage.