A gas laser generating device of the longitudinal gas flow type having at least two glow discharge tubes, each of which has positive and negative electrodes, electric insulating tubes which are inserted between the two glow discharge tubes in order to provide insulation therebetween, and mirrors which are positioned at the ends of the two glow discharge tubes. In the glow discharge tubes, gas is excited to generate gas lasing and this gas lasing is amplified by the reflections of the mirros. Also, there are further provided triggering electrodes near either the negative or positive electrodes of the glow discharge tubes, respectively, which triggering electrodes are connected to the positive electrodes through triggering resistors, respectively.