A discharge lamp lighting apparatus includes a first inverter, a second inverter to output a voltage whose phase is opposite to that of a voltage provided by the first inverter, a discharge lamp connected between a first output terminal of the first inverter and a first output terminal of the second inverter, a first current detection circuit arranged between a second output terminal of the first inverter and a common potential and having a first current detection element and a second current detection element that are connected in series, a second current detection circuit arranged between a second output terminal of the second inverter and the common potential and having a third current detection element and a fourth current detection element that are connected in series, and a protection circuit to detect a current abnormality according to a composite signal of outputs of the second and fourth current detection elements and stop the operation of the first and second inverters.