To enable to safely exit a working site even if a main power supply circuit part is switched off at finish of works.

A sheet-made balloon free in expansion and contraction and nearly wholly translucent is provided at an upper side of a support part, a light source device 12 is housed inside the balloon, a base part 13 retaining the light source part 12 is fixed to the support part, an air-feeding device 15 of air for balloon expansion is fitted at base part 13, and a main power source circuit for the light source device 12 and the air-feeding device 15 is made provided with an auxiliary light-emitting circuit 20 for connecting a battery part 18 and a light source 19 connected to the same 18 and for supplying power from the battery part 18 to the light source 19 based on switching-off operation of the main power source circuit.