A discharge lamp lighting circuit 1 has a DC power supply circuit 3 for outputting a DC voltage and a DC-AC conversion circuit 4 for converting the output voltage of the DC power supply circuit 3 into an AC voltage and then supplying the AC voltage to a discharge lamp 6. To light the discharge lamp 6, a predetermined period of time over which the polarity of the voltage supplied from the DC-AC conversion circuit 4 to the discharge lamp 6 is defined as either positive or negative and is provided before the discharge lamp 6 is lighted. The voltage polarity is forcibly inverted to limit the duration of the period so as not to exceed the predetermined time. The circuit reduces costs and prevents short life and degradation of a discharge lamp by placing a time limit on the duration of the period over which the supply voltage polarity is temporarily fixed before the discharge lamp is lighted.