PURPOSE: To enable a device to perform the detection of a fault of a display unit which is visually performed in the display control circuit which supplies a driving current to a switch connected in series with the display unit and controls the illumination and extinction of the display unit.

CONSTITUTION: The series circuit of a switch part 12 connected in series with a display unit 13 is provided with a detection part 14 which detects the presence or absence of a current flowing to the display unit 13 and this circuit is equipped with a control part 11 which outputs a signal indicating that the display unit is faulty when the detection signal from the detection part 14 indicates the absence of a current even if the driving current is supplied to the switch part 12.