Abstract: Disclosed is an electronic ballast for a HID lamp of a high wattage. A conventional AC voltage is filtered for rejecting a noise and is full-wave rectified. The rectified voltage is provided to a power-factor correction circuit. The power-factor correction circuit produces a boosted DC voltage with a high power-factor by charging capacitors while the rectified voltage transferred by a transformer is switched in a high frequency by a MOSFET. A high-frequency driving circuit produces a charge voltage with the boosted DC voltage, flows a discharge current by alternately switching in a high-frequency two switching circuits which use bipolar transistors coupled in a half-bridge type to discharge the charge voltage, and provides a driving power to the HID lamp while generating a resonance with an energy transferred by the discharge current. In order to drive a HID lamp of a high rating power, the switching circuits further includes transformers which enhance base currents of the bipolar transistors, respectively.