Abstract: A light source for ultraviolet ray irradiation, comprises a rod-shaped discharge lamp having an arc tube, wherein a chip formed in the arc tube is dented so as not to project from an outer surface of the arc tube, a cooling jacket having an inner pipe and an outside pipe, between which cooling fluid flows, wherein the discharge lamp is arranged so that a portion where the chip of the arc tube is formed is located in a lower portion in a gravity direction.

Abstract: An ultraviolet ray light source apparatus includes a discharge lamp in which a pair of electrodes are arranged inside an approximately rod shape arc tube, and a shrunk portion and a sealing portion are formed at both ends of the arc tube, a cooling jacket in which a lamp configuration space extending in parallel with the arc tube and is formed in a light emission section area of the discharge lamp, and a pair of lamp holders which supports the discharge lamp in the lamp configuration space, so that an axis of the arc tube is horizontally supported. The ultraviolet ray light source apparatus further comprises a cooling unit which sends cooling air toward an upper part of the shrunk portion at an end of the arc tube and a discharge section, provided below the shrunk portion, which discharges the cooling air.