In a discharge lamp lighting apparatus, in a starting sequence of a discharge lamp, while a frequency control circuit generates a inverter driving signal corresponding to resonance frequency of a resonant circuit, a power supply circuit outputs non-load open circuit voltage that is sufficient to maintain electric discharge, even when a boosting action accompanying a resonance phenomena disappears, and then a periodic drive circuit generates the inverter driving signal to gradually decrease frequency of the inverter from a frequency corresponding to the resonance frequency of the resonant circuit, until the frequency of the inverter reaches a first threshold frequency, and wherein when the frequency of the inverter reaches the first threshold frequency, while the periodic drive circuit generates the inverter driving signal so that the frequency of the inverter turns into a stable lighting frequency, the power supply circuit outputs current that is sufficient to maintain the electric discharge of the discharge lamp.