In at least one embodiment of the disclosure, a discharge lamp lighting device comprises a discharge lamp driving section, a state detecting section that detects a deterioration state of an electrode of a discharge lamp, and a control unit. The control unit alternately performs a first DC driving processing and a first AC driving processing in a first section of the driving current. The control unit alternately performs a second DC driving processing and a second AC driving processing in a second section of the driving current different from the first section. According to a progress of the deterioration state of the electrode, the control unit increases a length of at least one of: (i) a period for which the first DC driving processing is performed, and (ii) a period for which the second DC driving processing is performed.