To provide a beacon light, which can prevent snow, even if accumulated, from blocking illuminating light through a projection window by melting the snow without needing construction of a special cable line for a heater.

The beacon light includes a heater 108 which is electrically connected to a light emitting diode 107 in a serial relation, receives power from a constant current power source device 9 to melt the snow obstructing the illuminating light through the projection window 52; and a temperature detecting means 109 which detects temperature of the heater 108 and forms, when the detected temperature is a predetermined value or higher, an electric circuit bypassing the heater. The power can be supplied to the heater by use of the light emitting diode for lighting, and the power supply is stopped when the heater is not needed.