PURPOSE: To prevent contamination of a Brewster window due to graphite fiber in a gas flow type discharge process, by providing a gas introducing pipe which is protruded into the laser pipe from the anode side at the position which is deviated from the central axis of the laser pipe.

CONSTITUTION: The gas introducing tube 10, which is protruded into the laser tube from the side of the anode 1, is provided at the position deviated from the central axis of the laser tube. When the argon laser tube is manufactured by the gas flow type discharge, the graphite powder yielded from thin graphite pipe parts 3 is exhausted from the gas introducing pipe 10 together with the argon gas. Therefore, probability at which the graphite powder reaches the Brewster window 4 becomes very small. In this way, the contamination of the Brewster window due to the graphite power in the gas flow process can be prevented.