PURPOSE: To generate mg-power CO gas laser earns at a room temperature without adding Xe and Hg to the laser gas by connecting a high-frequency feeding means which supplies discharging high-frequency current to discharging electrodes whose facing direction is permitted to orthogonally intersect with the laser gas passage.

CONSTITUTION: A discharging part 2 is provided with a pair of discharging electrodes 3A and 3B which are insulated from the partition walls of a laser gas passage 1, and the facing direction of the discharging electrodes 3A and 3B is permitted to orthogonally intersect with the laser gas passage 1. The laser beam axis is permitted to alternately intersect orthogonally with the laser gas passage 1 and the facing direction of the discharging electrodes 3A and 3B. A high-frequency feeding means 4 supplies the discharging electrodes 3A and 3B with high-frequency waves of 1-250 mega Hertz so as to permit the electrodes to discharge. Thus, even when Xe and Hg are not added to the laser gas, highly efficient and high-power CO gas laser beams are generated at a room temperature.