A discharge lamp lighting device includes: a power converting circuit including a step-down chopper circuit and a polarity inversion circuit configured to convert an output from the step-down chopper circuit to a rectangular-wave alternating-current voltage, and thus to apply the rectangular-wave alternating-current voltage to a discharge lamp; and a memory configured to store a history of an output from the power converting circuit in a previous stable lighting mode. A control circuit controls on and off of each of switching elements in the step-down chopper circuit and the polarity inversion circuit, and thereby changes the output from the power converting circuit in a predetermined time period after the lamp starts lighting until reaching a stable lighting state on the basis of the history stored in the memory, so that a rise of a lamp voltage is suppressed. This enables extension of the lifespan of the lamp and suppression of the occurrence of arc jump.