Recently, a Mercury-free flat fluorescent lamp has been developed, which shows a high brightness (>5000cd/m2) and high luminous efficacy (60lm/W). Additionally, it has a wide operating margin and stable driving condition with the aid of an auxiliary electrode. For driving the lamp, a narrow pulse power to maintain the glow discharge state is required. Since the conventional circuits are hard to obtain the lamp driving, new short-pulse high-voltage lamp ballast is developed. The proposed ballast uses coupled-inductor in order to enhance short pulse up to the lamp ignition level and obtain energy-recovery action, as well. The operation principle and experimental results are included. The ballast is adequate for driving the flat lamp with high system efficiency and low cost.