A steering wheel heater device comprising: a plurality of steering wheel heaters each configured of an electrical resistor which produces heat by electrical energy, each of the plurality of steering wheel heaters having a first terminal and a second terminal and being included in a steering wheel; a plurality of first inductors (Lb) each connected in series to the first terminal of each of the plurality of steering wheel heaters ; at least one switch (101; 102) for turning on and off supply of power to the plurality of steering wheel heaters ; and a sensor circuit electrically connected to the first terminals of the plurality of steering wheel heaters and to the plurality of first inductors (Lb), for determining whether a detected subject is in contact with the plurality of steering wheel heaters , based on a magnitude of capacitance of each of the plurality of steering wheel heaters , wherein the at least one switch is at least one of a first switch connected in series via the plurality of first inductors (Lb) to the first terminal of each of the plurality of steering wheel heaters and a second switch connected in series to the second terminal of each of the plurality of steering wheel heaters , and the steering wheel heater device further comprises a controller for determining valid periods in each of which the sensor circuit determines whether the detected subject is in contact with respective one of the plurality of steering wheel heaters , and for disabling the sensor circuit during periods other than the valid periods, the valid periods synchronizing with an on-state and an off-state of the supply of power to each of the plurality of steering wheel heaters , and the controller enables the sensor circuit while switching between the plurality of steering wheel heaters in a time-sharing manner. a plurality of steering wheel heaters each configured of an electrical resistor which produces heat by electrical energy, each of the plurality of steering wheel heaters having a first terminal and a second terminal and being included in a steering wheel; a plurality of first inductors (Lb) each connected in series to the first terminal of each of the plurality of steering wheel heaters ; at least one switch (101; 102) for turning on and off supply of power to the plurality of steering wheel heaters ; and a sensor circuit electrically connected to the first terminals of the plurality of steering wheel heaters and to the plurality of first inductors (Lb), for determining whether a detected subject is in contact with the plurality of steering wheel heaters , based on a magnitude of capacitance of each of the plurality of steering wheel heaters , wherein the at least one switch is at least one of a first switch connected in series via the plurality of first inductors (Lb) to the first terminal of each of the plurality of steering wheel heaters and a second switch connected in series to the second terminal of each of the plurality of steering wheel heaters , and the steering wheel heater device further comprises a controller for determining valid periods in each of which the sensor circuit determines whether the detected subject is in contact with respective one of the plurality of steering wheel heaters , and for disabling the sensor circuit during periods other than the valid periods, the valid periods synchronizing with an on-state and an off-state of the supply of power to each of the plurality of steering wheel heaters , and the controller enables the sensor circuit while switching between the plurality of steering wheel heaters in a time-sharing manner. <EOS>