PURPOSE: To provide a lighting device of a gas lamp capable of reducing mistaken lighting.

CONSTITUTION: This lighting device 10 is adapted such that diffused and mixed gas after blown off from a burner 23 disposed in a fire chamber of a gas lamp toward a mantle 17 is lighted using spark electric discharge. A positive electrode 30 of the lighting device 10 is disposed outside a peripheral wall of the mantle while a negative electrode 22 corresponding to the positive electrode 30 is disposed inside the peripheral wall of the mantle 17. An outside surface side of the peripheral wall of the mantle 17 is used as a lighting portion.