Abstract: A screw-based incandescent lamp type fluorescent lamp comprises a luminous tube bent to define a vacant space therein, a ballast for said luminous tube disposed in said vacant space, a holder having an opening facing said ballast at a given distance therefrom and holding said luminous tube and ballast, a basal body supporting said holder, in which upper ventilation slits are formed, and a light transmitting bottomed envelope attached to said basal body to form an outer tube and having a lower ventilation opening with an opening area smaller than the total area of said upper ventilation holes, whereby air introduced from said lower ventilation opening into said bottomed envelope will flow along the outer peripheral surfaces of said ballast and said luminous tube and be discharged from said upper ventilation slits to the outside via the opening of said holder.