The present invention provides a method of reducing an amount of NOx generated in actuation of a hybrid inflator. The present invention is a method of reducing nitrogen oxide which is generated in actuation of a hybrid inflator for an inflatable safety system of a vehicle provided with an airbag, the inflator comprising an inflator housing charged with a pressurized medium, a gas generator which is accommodated in the inflator housing and has one or two or more gas generating chambers storing a gas generating agent including a fuel and an oxidizing agent, and an igniting means connected to the gas generator, wherein a reducing compound having at least a reducing function of a nitrogen oxygen is placed in the hybrid inflator.