PURPOSE: To enable to discharge-excited gas laser oscillator to stably maintain a desired laser output for a long period by providing a discharging voltage adjusting means and gas pressure adjusting means to the laser oscillator.

CONSTITUTION: This discharge-pumped gas laser oscillator 20 is provided with a discharging voltage adjusting means 1 and a gas pressure adjusting means 2 composed of a gas inlet valve 2a and gas exhaust valve 2b. These adjusting means 1 and 2 are operated through a manual controlling mechanism, etc. Therefore, a desired laser output can be obtained at desired timing even during laser oscillation and, at the same time, a stable laser output can be obtained for a long period by finely adjusting the discharging voltage adjusting means 1 and/or gas pressure adjusting means 2.