EXTREME ULTRAVIOLET LIGHT SOURCE DEVICE

PROBLEM TO BE SOLVED: To appropriately determine a timing to replace an extreme ultraviolet (EUV) collector mirror by accurately considering influence of a sputtering amount of the mirror in a laser-produced plasma (LPP) EUV light source device.SOLUTION: An EUV light source device comprises: a sputtering amount detector which is arranged in a vacuum chamber and has a sensor with a film formed on its surface, and monitors a change in film thickness caused when ion-containing particles generated from plasma sputter the film formed on the sensor surface, thereby outputting a detection signal indicating the change in film thickness; a calculation unit which calculates an amount of change in film thickness based on the detection signal output from the sputtering amount detector; and a determination unit which outputs a determination signal indicating a timing to replace or repair a collector mirror when the amount of change in film thickness calculated by the calculation unit reaches a predetermined reference value.