A flat lamp is provided, including an upper plate and a lower plate arranged to face each other at a predetermined distance; a plurality of spacers installed between the upper plate and the lower plate to form discharge spaces; a first and second electrodes provided in a stripe form on the outer surface of the upper plate or the lower plate with the respective discharge spaces located thereon; a first and second inner electrodes provided within each of the spacers; and a fluorescent layer formed on each of inner surfaces of the upper and lower plates and each of the outer surfaces of the spacers.