A hot cathode type low-pressure rare gas discharging fluorescent lamp comprising a glass bulb (1,11) and a pair of electrodes (12a,12b) including an electrode acting as a hot cathode at least in a stable discharging state, said paired electrodes being provided within said glass bulb (1,11), is characterized in that a fluorescent substance layer (13) is formed on the inner surface of said glass bulb (1,11); a light emitting gas (14) is sealed in the interior of said glass bulb (1,11), said fluorescent substance layer (13) is rendered luminous by radiation emitted from said light emitting gas (14), a partial pressure of said sealed, light emitting gas (14) is not higher than 5 Torr, and said light emitting gas (14) comprises at least krypton.