The invention relates to an activation unit for a safety system of a motor vehicle, comprising a pyrotechnic gas generator and a drive unit operatively connected to the pyrotechnic gas generator for converting the gas stream exiting upon activation of the gas generator into a rotational movement of a rotor connectable to the safety system. In order to provide an activation unit which is constructed in a particularly compact manner and thereby exhibits a high rotational movement, it is provided that the drive unit has at least two drive chambers arranged in the flow direction of the exiting gas, each having an inlet opening and an outlet opening for a fluid or gas, with each having a drive body which can be operatively connected to the rotor.
