A high frequency discharge excited coaxial type CO.sub.2 laser is provided, which has both the advantageous characteristic of high frequency excitation type, namely, small size and high efficiency, and the advantageous characteristic of coaxial type, namely, high quality beam mode. This laser includes a dielectric laser tube and two helical electric conductors of the same pitch, and a high frequency voltage is applied between the conductors by a high frequency power source while the CO.sub.2 laser gas is passed axially in the laser tube.