A discharge lamp lighting device includes a discharge lamp, a resonant circuit section, a power conversion section, and a control section. The resonant circuit section is connected to the discharge lamp. The power conversion section is adapted to convert direct-current power into alternating-current power and then supply the discharge lamp with the alternating-current power via the resonant circuit section. The control section is adapted to change a frequency of the alternating-current power alternatingly between a first frequency and a second frequency different from the first frequency in a lighting start period until the discharge lamp reaches a stationary lighting state. The control section is adapted to change the first frequency toward a frequency causing a resonance of the resonant circuit in a stepwise manner. The second frequency is lower than the first frequency.