A gas generator comprises an elongated, preferably tubular outer housing (10), at least one combustion chamber (26, 28) provided therein and filled with a solid propellant (30; 30′), and at least one igniter unit (16, 18) generating ignition gas for igniting the solid propellant (30; 30′). The igniter unit (16, 18) is arranged laterally and externally on the outer housing (10) in such a way and, in relation to the outer housing (10), a preferably radial ignition transfer opening (50, 58) is provided in the outer housing so that ignition gas generated in the igniter unit (16, 18) flows into the interior of the outer housing (10) via the ignition transfer 1 openings (50, 58).