A CO.sub.2 gas laser device comprises a plurality of divided cathode electrodes disposed in a linear row extending transversely across a high-speed flow of a gas containing CO.sub.2, and parts of the cathode electrodes producing negative glow are disposed at the same height as anodes at a downstream position. Additionally, a device for controlling the distribution of gas flow velocity, which functions doubly as means for creating turbulent flow, and a preliminary discharge electrode are disposed on the upstream side of the cathode electrodes, the former being set at a height position corresponding substantially to that of the middle portions of the cathode electrodes.