A fluorescent discharge lamp of improved light output having a plurality of phosphor layers stacked on a substrate of a glass tube so that the concentration of activator for the phosphor layer located near the glass substrate is less than that for the phosphor layer located at a position remote from the glass substrate, thereby to form phosphor layer having a low reflection factor to an ultraviolet ray on the electric discharge side, and a phosphor layer of enhanced quantum efficiency and high reflection factor to the ultraviolet ray on the side of the glass substrate. The ultraviolet ray generated with an electric discharge is caused to be absorbed as much as possible by the phosphor layers thereby to improve the light output. The lamp is used in, for example the field of illumination.