A method for driving a discharge lamp that lights by performing discharge between two electrodes while alternately switching a polarity of a voltage applied between the two electrodes includes: modulating an anode duty ratio, which is a ratio of an anode time for which one of the electrodes operates as an anode in one period of the polarity switching, by setting first and second periods with different anode duty ratios; and setting the first period, in which the anode duty ratio is higher than that in the second period, longer than the second period in one modulation period, which includes the first and second periods and for which the modulation is performed, when a predetermined condition is satisfied.