The present invention relates to an extra-high pressure mercury lamp in which 0.15 mg/mm3 or more of mercury is filled as light emitting material, and a pair of electrodes facing each other is disposed in an arc tube, in which at least one of the pair of electrodes has an axis portion, and a thick diameter portion formed by winding a coil around the axis portion, the thick diameter portion comprising a winding portion provided on the axis portion, and a curvature portion which is integrally formed with the axis portion, and has a curved portion at least in part around a circumference of the axis portion between the axis portion and the curvature portion, and the curved portion connected to a back end portion of the winding portion.