To provide an excimer lamp device which is of such a construction that no friction between a lamp support and a material to be treated occurs by keeping the position of the lamp support installed in a long enclosure constant all the time, and a change in the position of the lamp support due to the thermal distortion of a barrier can be eliminated, as well as the corrosion of equipment mounted inside the enclosure due to the ozone generated at the periphery of an excimer lamp can be prevented from occurring.

The excimer lamp device 1 comprises the enclosure 1, a suspension 4 supported by the enclosure 1, a lamp support 6 braced by the suspension 4, an excimer lamp 5 supported by the lamp support 6, and the partition wall 7 installed between the excimer lamp 5 and the suspension 4. The lamp support 6 is loosely inserted into a through-hole 8 opened in the partition wall 7 and supported by the suspension 4. In addition, an adjustment means is installed which adjusts the position, in the vertical direction, of the lamp support 6 to the suspension 4, and also a shielding means is installed which prevents a gas from passing between the through-hole 8 and the lamp support 6 which is inserted loosely into the through-hole 8.