A magnetostriction type torque sensor is provided which includes magnetic property change material which is provided on a shaft and whose magnetic property changes in accordance with torque applied to the shaft, an excitation signal generator which generates an excitation signal whose voltage is converted into a predetermined voltage through a switching element, a plurality of detection coils to which the excitation signal generator applies the excitation signal, and which plurality of detection coils outputs voltage, which changes in accordance with change in the magnetic property of the magnetic property change material, between connection points between the detection coils, and an operational state monitor which monitors an operational state of the switching element.