The flat noble-gas discharge lamp of the present invention includes an outer enclosure that has a rear-surface substrate and a light-extraction-side substrate that is positioned to confront the rear-surface substrate. A first fluorescent film and a second fluorescent film that emit visible light of different colors are formed on respective inner surfaces of the rear-surface substrate and the light-extraction-side substrate; a first electrode and a second electrode are formed at a distance from each other on the rear-surface substrate; and a third electrode that confronts both of the first electrode and second electrode is formed on the light-extraction-side substrate. The application of voltage between the first electrode and the second electrode generates a glow discharge based on dielectric barrier discharge in the vicinity of the rear-surface substrate inside the outer enclosure, while the application of voltage between the first and second electrodes and the third electrode generates a glow discharge in the central region of the interior of the outer enclosure; and the ultraviolet rays that are generated by the glow discharge are converted to visible light by the first and second fluorescent materials.