A discharge lamp lighting apparatus for lighting a discharge lamp in which an electric discharge medium, which contains xenon, is enclosed in an electric discharge container, and a pair of cathode electrode and anode electrode for main discharge is arranged to face each other, comprises a starter for generating dielectric breakdown in the electric discharge container of a discharge lamp, and a power supply circuit for supplying discharge current to the discharge lamp, wherein the power supply circuit has an output current modulation circuit for modulating the magnitude of current passed through the discharge lamp in at least a lighting steady state, according to a modulation signal, and wherein the output current modulation circuit controls speed of change so as to be 2.6 A or less per millisecond in case the magnitude of the lamp current per square millimeter in a cross section of the cathode electrode decreases.