A laser oscillator device applies a high-frequency voltage to a plurality of discharge regions through a dielectric for producing a high-frequency discharge for laser pumping. The laser oscillator device includes a DC power supply (16), and a high-frequency power supply (18, 19, 20, 21) for converting a DC voltage into a high-frequency voltage. The DC power supply (16) and the high-frequency power supply (18, 19, 20, 21) are coupled to each other by a filter (30). The filter (30) prevents a high-frequency component from being fed back from the high-frequency power supply (18, 19, 20, 21) to prevent the laser oscillator device from operating unstably due to parasitic oscillation. Other arrangements are disclosed for preventing interference between the high-frequency power supply and the DC power supply.