A CO₂ gas laser device comprises a plurality of cathode electrodes (7) disposed in a linear row extending transversely across a high-speed flow of a gas containing CO₂, and parts of the cathode electrodes (7) producing negative glow are disposed at the same height as anodes (6) at a downstream position. Additionally, a device (9) for controlling the distribution of gas flow velocity, which functions doubly as means for creating turbulent flow, and a preliminary discharge electrode (l0) are disposed on the upstream side of the cathode electrodes (7), the former being set at a height position corresponding substantially to that of the middle portions of the cathode electrodes (7).