An arrangement for fixing a gas generator of an air bag unit. The gas generator is securely fixed in the generator chamber and both radial and axial tolerances, in particular of the gas generator, are compensated using a plate-like, spring-elastic fastening element that is pressed in the area of the end of the gas generator lying opposite the fixed bearing between the outer circumference thereof and the inner circumference of the generator chamber axially projecting through the gas generator. After the pressing in, the fastening element is arched into the generator chamber in the axial direction in a section between the outer wall of the gas generator and the inner wall of the generator chamber in the axial direction.