Mercury lamp of the short arc type and UV emission device

A mercury lamp of the short arc type which can stably emit an intense spectrum at a wavelength of 365 nm with an extremely narrowed band region over a long time, and which has an anode and a cathode disposed opposite one another in a silica glass arc tube which is filled with mercury and a rare gas, is achieved by the amount of mercury being less than or equal to 1.0 mg/cc of the inside volume of the arc tube and at least one of the gases argon (Ar) and krypton (Kr) are used as the rare gas at room temperature with 1.0 to 8.0 atm.