The present invention includes: first to fourth Hall elements for detecting steering torque; a first power supply circuit for supplying power to the first and second Hall elements; a second power supply circuit for supplying power to the second and third Hall elements; and a control device including a first abnormality determining unit for determining whether first and fourth torque signals are abnormal by preparing the first torque signal output from the first Hall element with the fourth torque signal output from the fourth Hall element and a second abnormality determining unit for determining whether second and third torque signals are abnormal by comparing the second torque signal output from the second Hall element with the third torque signal output from the third Hall element. With this, even when abnormality occurs in one of the first and second power supply circuits, the abnormality determination of an output signal can be continued.