A torque detection apparatus includes a torque sensor, a sensor circuit, a signal processing circuit, and an abnormal state monitoring circuit. The torque sensor is arranged on a rotary shaft and operates to output a predetermined electric signal related to a torque applied to the rotary shaft. The sensor circuit outputs the predetermined electric signal as a sensor circuit signal. The signal processing circuit processes the sensor circuit signal in order to output a torque detection signal. The abnormal state monitoring circuit is arranged proximate the signal processing circuit and operates according to the sensor circuit signal to detect an abnormal operation.