In the manufacture of arc tubes for use as light sources of vehicle headlamps, there is first prepared a semifinished arc tube by inserting one electrode assembly into a tubular glass envelope through one end thereof and by sealing this end. The semifinished arc tube is then placed in communication with a hermetically enclosed space filled with argon under pressure, with the consequent introduction of the inert gas into the glass envelope through a second end thereof. Another electrode assembly and chemicals such as a metal halide and mercury are then introduced from the enclosed space into the semifinished arc tube through the second end, totally without contact with the atmospheric air. Then, with the glass envelope placed out of communication with the enclosed space, the argon is exhausted from within the envelope, and xenon is charged instead into the envelope through the second end, which is closed subsequently.