To provide a marker light for wearing a helmet capable of surely informing the whereabout of oneself in the dark and further ensuring the safety of a guard, etc., by attaching thereof to a helmet worn by the guard, an operator, etc., in a site of construction.

This marker light for wearing a helmet 1 is obtained by installing each light emitting diode(LED) 3 in a state thereof slightly protruding from the outer periphery of the helmet 1, connecting the LED 3 through each lead wire 5 to a battery box 7 as a holder, housing a dry battery or cell and an flashing circuit in the battery box 7, connecting the LED 3 through the flashing circuit to the dry battery or cell and installing a switch in the battery box 7. The marker light for wearing the helmet 1 is composed of the LEDs 3, the lead wires 5, the battery box 7 and the dry battery or cell and the flashing circuit housed in the battery box 7.