A power supply for discharge lamp includes a transformer and a current balance device, wherein the transformer includes a primary winding and a secondary winding and the current balance device is coupled between the secondary winding and a plurality of discharge lamps. The current balance device may include a single inductor wherein at least two windings are connected in series with each other and each serially-connected winding is coupled with a discharge lamp, and the other windings are respectively coupled with a discharge lamp. The current balance device may include two inductors wherein at least one winding of a first inductor is connected in series with at least one winding of a second inductor and each serially-connected winding is coupled with a discharge lamp, and the other windings of the first inductor and the other windings of the second inductor are respectively coupled with a discharge lamp.