A discharge lamp has an electrode comprising a base portion having a base portion side flange portion, and a lid portion having a lid portion side flange portion. In a sealed space of the electrode, heat conductive member is enclosed. At time of lighting, the electrode is not damaged, and the discharge lamp can be stably operated. In the electrode, the diameter direction width of a welding portion of a base portion side flat portion and a lid portion side flat portion is 0.8 to 3.0. Further, an angle formed by the base portion side flat portion and a base side slope portion is 30 degrees or less and an angle formed by the lid portion side flat portion and a lid side slope portion is 30 degrees or less. The sum total of these angle is 160 degrees or less.