PURPOSE: To enable a cornering lamp to be lighted only when needed so as to enhance practical usage thereof by lighting the cornering lamp only when a direction indicator switch is operated and a vehicle starts torning run.

CONSTITUTION: With a lighting switch 7 on at night or at other times required and with the illuminating element D of a turing run detector 8 fed with a current, when the movable contact 3a of a direction indicating switch 3 is turned to the side of the left-turn fixed contact 3b, for example, to flicker a left-turn direction indicator 1 at the flashing interval of a flasher unit 5, the first integrating circuit 12e of a flasher signal discriminating circuit 12 generates a signal of a H level. When a steering handle is steered to turn a vehicle to the left, a rotary disk 8a is, at this time, turned synchronously and a light receiving element Tr senses the illumination of the illuminating element D to generate a signal of a H level. Along with the generation, a running state signal retaining circuit 13 changes the output level to H to excite a relay 15, which makes a left- turning cornering lamp 9 to be lighted.