A method for driving a discharge lamp that supplies an AC current to a discharge lamp having a first electrode and a second electrode so as to produce discharge and to cause the discharge lamp to emit light includes the steps of, during a steady operation in which the AC current is supplied to the first electrode and the second electrode, when power of the same amount is fed to the first and second electrodes, and a tip portion of the first electrode becomes higher than a tip portion of the second electrode in temperature, changing the duty ratio of the AC current to be supplied between the first electrode and the second electrode in accordance with a predetermined pattern, and setting a current value when the first electrode operates as an anode during one cycle so as to be smaller than a current value when the second electrode operates as an anode during one cycle.