An LPP EUV light source device for forming a uniform droplet target regardless of a frequency of a drive signal applied to a vibrator. The LPP EUV light source device includes: a chamber in which the extreme ultra violet light is generated; an injection nozzle that injects a target material into the chamber; a vibrator that has two terminals and vibrates to provide vibration to the injection nozzle when a drive signal is applied between the two terminals via a cable; a voltage generator that generates the drive signal; a controller that monitors a voltage between the two terminals of the vibrator and feedback controls the voltage generator such that an amplitude of the monitored voltage falls within a predetermined range; and a laser source that generates a laser beam to be irradiated to the target material injected from the injection nozzle.