Abstract: A ballast for discharge lamp. The ballast for discharge lamp for utilizing high frequency voltage is generated by alternatively switching two switching elements to light the discharge lamp. The ballast includes a primary winding of a switching transformer to which the high frequency voltage is applied; a secondary winding of a switching transformer for alternatively switching the two switching elements according to reverse electromotive voltage generated by application of high frequency voltage to the primary winding; and a stabilizer for stabilizing reverse electromotive voltage generating at the secondary winding.