A sensor device includes a main sensor, a sub sensor, and an Electronic Control Unit (ECU). The ECU has a torque calculator that sets, as a steering torque, a main steering torque that is calculated based on a main sensor signal when a main output signal is normal. During a transition period between an abnormality detection and an abnormality establishment regarding the main output signal, the torque calculator calculates the steering torque based on (i) a sub steering torque calculated based on a sub sensor signal and (ii) a prior-to-abnormality-detection main steering torque. In such manner, even when abnormality is detected in a part of the sensor signals, a fluctuation of the steering torque due to, or accompanying, the switching of the steering torque calculation to a normal signal only calculation is prevented.