To suppress electric power applied to a semiconductor switch device to suppress its generation of heat by reducing the ON duty ratio of an intermittent ringing input to the semiconductor switch device when the semiconductor switch device abnormally generates heat due to any reason.

A flash circuit 21A, a semiconductor switch device 21B and a device temperature sensor part 21C are integrated to constitute a module body 21, and the device temperature sensor part 21C is connected to the flash circuit 21A. An intermittent ringing is directed from the flash circuit 21A to the semiconductor switch device 21B to cause direction indicator lamps 1R and 1L connected to the semiconductor switch device 21B to flash for turn signaling. The device temperature sensor part 21C detects the heating temperature of the semiconductor switch device 21B to reduce the ON duty ratio of the intermittent ringing when the detected temperature gets higher.