Each of detection units detects electrostatic capacitance values Cc, Cr, Cl produced between sensors and a passenger H, based on electrical signals Sc, Sr, Sl outputted from the sensors, respectively. A total value calculation unit sums electrostatic capacitance values Cc, Cr, Cl to calculate a total value Ct of the electrostatic capacitance values Cc, Cr, Cl. A comparison determination unit compares the total value Ct with a first threshold value Cth1 to make a contact determination of whether the passenger H is in contact with a steering wheel.