An ultra high pressure mercury lamp having a light emitting part, a pair of electrodes; hermetically sealed portions; part of the electrodes and metal foils installed in the hermetically sealed portions and connected to the base parts of the electrodes; and outer leads connected to the base parts of the metal foils. The metal foils have a region with a small width which is groove-shaped and with which the electrodes are connected, and a wide region which borders the region with a small width, and which has an Ω-shaped end region which borders the groove of the region with a small width, in which an end groove is formed, and which extends in the lengthwise direction, a base-side Ω-region which is connected to the outer lead, in which a base-side groove is formed, and a middle, flat region which extends between the end Ω-region and the base-side Ω-region.