Abstract: A vehicle includes a plurality of switch devices including respective LEDs, which are turned on to illuminate when a lighting switch for headlights and taillights is activated. A current flowing in one of the switch devices is detected and a current supplied from a battery to the switch devices is controlled by a regulator circuit and a single transistor based on the detected current. A voltage corresponding to a battery voltage is superimposed on a current detection voltage, and the regulator circuit immediately stops the current when the battery voltage excessively increases.