In at least one embodiment of the disclosure, a discharge lamp lighting device comprises a discharge lamp driving section and a control unit. The control unit alternately performs a first DC driving processing and a first AC driving processing in a first portion of the driving current. The control unit alternately performs a second DC driving processing and a second AC driving processing in a second portion of the driving current different from the first portion. The control unit performs the first AC driving processing and the second AC driving processing such that a frequency of a first alternating current and a frequency of a second alternating current have different values.