Discharge lamp lighting device and illumination fixture and projector using the same

[Object] To provide a discharge lamp lighting device which can reduce size and costs while securing startability of a discharge lamp, and an illumination fixture and a projector using the discharge lamp lighting device. [Means for Settlement] A discharge lamp lighting device includes a polarity inverting circuit 12 for supplying a rectangular wave voltage to a discharge lamp La, a resonance circuit 2 for supplying a starting output voltage to the discharge lamp La, a voltage detecting circuit 3 for detecting an output voltage and a control circuit 4 for setting a frequency of a rectangular wave voltage based on a detection result of the voltage detecting circuit 3 so that the output voltage of the resonance circuit 2 exceeds a starting voltage of the discharge lamp La. The resonance circuit 2 includes a resonance inductor T20 formed of an auto transformer inserted between a first output end P1 of the polarity inverting circuit 12 and the discharge lamp La, and a resonance capacitor inserted between an intermediate tap nc of the resonance inductor T20 and a second output end P2 of the polarity inverting circuit 12. The voltage detecting circuit 3 is constituted so as to detect the output voltage based on a potential of the resonance capacitor C20.