A fluorescent lamp may include a pair of hot cathode electrodes at both its ends, wherein a phosphor is formed in a laminated manner on the inner surface of a glass tube and a protection film is formed between the glass tube and the phosphor, wherein a residual impure gas in the lamp, including the amount occluded by the phosphor and the protection film, is set to 0.5% or less with the sealed rare gas partial pressure ratio, and wherein the following relationship is fulfilled: GHg=A×CL, A=0.0032-0.163 [mg/cc], wherein the amount of sealed mercury is GHg [mg], the lamp internal volume is CL [cc], and the coefficient is A [mg/cc].