A flat lamp is provided. The provided flat lamp includes an electrode unit generating an electric field in a discharge area between a front plate and a rear plate to generate a gas discharge, and spacers arranged between the front plate and the rear plate while having first portions contacting the inner surface of the front plate or the rear plate and second portions contacting the inner surface of the other plate. The second portions of the spacers extend at least two directions centering around the first portions. A fluorescent material layer is formed on any portion in a discharge area, for example, on the inner surface of the front plate or the inner surface of the rear plate. In the provided flat lamp, visible rays are generated from portions where the spacers are formed. Thus, when the spacers do not absorb nor block ultraviolet rays, the spacers transfer the ultraviolet rays to the fluorescent layer formed on the inner surface of the front plate. In other case, fluorescent layers are formed on the inner surfaces of the spacers that contact the inner spaces of the spacers of generating separate discharges in order to generate visible rays. Accordingly, partial deterioration of luminance and unevenness of luminance are prevented.