PURPOSE: To provide a discharge lamp lighting device in which an inverter means is prevented from entering an advanced-phase mode.

CONSTITUTION: An output voltage of an inverter circuit 1 is raised to a no-load secondary voltage which is applied to a fluorescent lamp FL. The lamp voltage of the fluorescent lamp FL drops with a rise in the lamp current, and when the voltage detected by a lamp voltage detecting circuit 2 is lower than the voltage value of a reference power supply E3, the output voltage of the inverter circuit 1 drops to a voltage corresponding to a fully-lighted state. When the voltage detected has dropped below the voltage value of the reference voltage E2, the output voltage drops to a voltage corresponding to a dimmed state. By causing the fluorescent lamp FL to start a discharge, the lamp voltage and the lamp current converge to a portion where they overlap with lamp characteristics. As the lamp current of the fluorescent lamp FL increases, the lamp voltage drops, so that efficiency is enhanced and so that the lamp voltage does not rise more than necessary, thereby preventing the inverter circuit 1 from entering an advanced-phase mode.