To provide an electrodeless discharge lamp device with restraint of noises generated accompanying rapid change of voltage applied on an induction coil at light dimming.

The electrodeless discharge lamp device contains a bulb 1 to be an electrodeless discharge lamp with discharge gas sealed, and a concave part 11 housing an induction coil 23 is fitted at the bulb 1. High-frequency voltage is applied on the induction coil 23 from a high-frequency power supply circuit 32. At the time of light dimming, a voltage which lights the electrodeless discharge lamp and a voltage which cannot retain lighting are alternately applied. On an inner side surface of the concave part 11, a conductive film to be an electrode 19 for biasing is formed along the induction coil 23. The electrode 19 for biasing is connected to a high-potential electrode of a direct current power supply circuit 31 through a switching element Q4. While the voltage which cannot retain lighting to the induction coil 23 is applied, the switching element Q4 is switched on, and a positive voltage is applied on the electrode for biasing 19 to generate repulsive force between the bulb 1 and ions.