A discharge lamp driving device includes a power stage circuit, a transformer circuit, a control circuit, a feedback circuit and a lamp protection circuit. The lamp protection circuit includes a current sensing circuit, a reference voltage selecting circuit, a comparing circuit and a protection signal generating circuit. The current sensing circuit senses current signals flowing through the lamps, and transforms the current signals to voltage signals. The reference voltage selecting circuit is connected to the current sensing circuit. The comparing circuit is connected to the current sensing circuit and the comparing circuit. The protection signal generating circuit is connected between the comparing circuit and the control circuit. The control circuit is connected to the comparing circuit.