The invention provides an excimer lamp apparatus that has advanced start-up properties, in terms of start-up time and start-up stability, in the presence of voltage variations, without any trigger electrode, by arranging a pair of electrodes along the entire length of a discharge container. An ultra-violet emitter is arranged to irradiate discharge gas in the discharge container with ultra-violet light, and the excimer lamp is started up by means of exposure with ultra-violet light from the ultra-violet emitting unit.