A discharge lamp ballast apparatus includes an F/F 10 for maintaining the on or off operation of a high-side switching device Q1 of an inverter in synchronization with a rising edge and falling edge of a main signal, and a return unit 9 for generating a signal for returning, even if the output Q of the F/F is inverted owing an unforeseen situation, the output to the polarity to be output normally; and returns the output of the F/F 10 to the first polarity to be output normally using the return signal.