In a mercury free arc tube provided with a sealed glass chamber in which at least metallic halide for main light emission is sealed as well as rare gas by pinch-sealing both end openings of a glass tube and electrode bars are opposite to each other, the tip of a region projecting into the sealed glass chamber of each the electrode bars is formed of a single crystal. Owing to repetition of ON/OFF of the arc tube, the crystal at the tip of the electrode bar grows but the shape of the electrode end face formed of the single crystal remains unchanged. Further, even if the tip of the electrode bar is gradually consumed by thermal load acting on the tip of the electrode bar, the entire shape of the electrode end face is consumed nearly uniformly so that decline of the luminescent spot does not occur during discharging.