The ultraviolet light-emitting device includes a base, a nitride semiconductor ultraviolet light-emitting element flip-chip mounted on the base, and a lens for sealing a nitride semiconductor ultraviolet light-emitting element to focus or diffuse light emitted from the nitride semiconductor ultraviolet light-emitting device. The lens is composed of an amorphous fluororesin in which a structural unit of a polymer or copolymer has a fluorine-containing aliphatic cyclic structure and a terminal functional group is a perfluoroalkyl group, and a density of the amorphous fluororesin is higher than 2.11 g/cm3.