A discharge lamp lighting apparatus is provided with a pulse generation part, and a power supply part converts DC applied voltage into alternating current corresponding to a frequency of the pulse, and supplies the alternating current to the discharge lamp. The pulse generation part is structured to alternately output a first pulse and a second pulse that has a lower frequency than the first pulse. The frequency of the second pulse is set to a predetermined reference frequency when a value of the applied voltage coincides with a predetermined reference value, is set to a lower frequency than the reference frequency when the value of the applied voltage exceeds the reference value, and is set to a frequency that is equal to or lower than the reference frequency when the value of the applied voltage falls below the reference value.