The present invention provides a gas generator includes a water tank, an electrolysis device, a condensate filter, a humidification device, and a pump device. The electrolysis device is coupled to the water tank to electrolyze electrolyzed water accommodated in the water tank to generate a hydrogen-oxygen mixed gas. The hydrogen-oxygen mixed gas is condensed and filtered out electrolyte in the hydrogen-oxygen mixed gas by the condensate filter to generate a filtered hydrogen-oxygen mixed gas. The humidification device accommodates supplementary water and is connected to the condensate device for humidifying the filtered hydrogen-oxygen mixed gas. The supplementary water is pumped back to the water tank from the humidification device by the pump device； therefore, the electrolyte absorbed in the condensate filter is flushed back to the water tank for reducing the consumption of the electrolyte.
