A discharge lamp includes a glass tube having electrodes with an electron emissive material coated thereon, the electrodes being provided on respective ends of the glass tube, wherein the glass tube has a gas containing a luminescent material sealed therein and has a fluorescent material coated on its inner surface, the glass tube has a diameter less than 6.5 mm and the gas sealed into the glass tube is gases of more than one kind selected from an Ar (argon) gas , a Kr (krypton) gas and a Xe (xenon) gas or a mixed gas mainly made of gases of more than one kind selected from the Ar gas, the Kr gas and the Xe gas. Thus, the discharge lamp can reduce a diameter of its tube and it is able to provide high luminous efficiency.