The present invention relates to a device in which a laser medium in a discharge space is excited by a discharge. The device includes a positive electrode and a plurality of negative electrodes in opposition, connected to a simmer power source and a main discharge power source. There is also a plurality of first stabilized resistances, which restrict the current of the simmer power source, each of which is respectively connected to one of the negative electrodes. There is also a plurality of first reverse current prevention elements, each of which is connected to the main discharge power source, and connected in parallel with one of the first stabilized resistances.