A lighting apparatus for a high-pressure discharge lamp that has an electric discharge container made of quartz glass, and containing a pair of counter electrodes and a power supply unit that supplies AC current to the high-pressure discharge lamp. The power supply unit has a stationary power lighting mode and a modulated power lighting mode that supplies current having power less than power in the stationary power lighting mode. The modulated power lighting mode supplies a rectangular AC current having a first term and a second term. A mean high-frequency current value supplied to a first electrode is greater than a mean current value supplied to a second electrode in the first term. A current is supplied to the second electrode for a term longer than the half-cycle period in the second term, the current being lower than the mean high-frequency current value supplied to the first electrode.