To provide a discharge lamp lighting device which can restrain electrical stress against switching elements and inductors using a simple control circuit and prevent parts from increasing in cost and enlarging their sizes to control measure for changes in source voltage, light adjustment or the like, while conducting frequency modulation.

The discharge lamp lighting device 1 comprises a high-frequency power source part formed by an one-element type voltage resonance circuit having a first switching element SW1, a power source adjustment part for adjusting output from a DC power source E to the high-frequency power source part by a switching operation of a second switching element SW0 and a load circuit, including a discharge lamp RL to which high-frequency power from the high-frequency power source part, is supplied. A control unit 2, which makes the turn-off time and turn-on time of a switching operation of the first switching element SW1 fixed and variable, respectively, and makes at simultaneous turn-on period during which the turn-on time of the switching operation of the second switching element SW0 overlaps the turn-on time of the first switching element SW1 a prescribed length is provided.