To provide a safety device suitable for use in a biomass gasificating generation fixed bed gas generator.

The safety device for the gas generator comprises a water sealed liquid-column gage 10 provided in the gas generator for allowing the release of gas generated in the generator from the liquid-column gage 10 when gas overpressure occurs in the gas generator. The water sealed liquid-column gage 10 has a communication pipe 6 one end of which is communicated with the generator and the other end of which is inserted into a water container and the water container 7 for storing water. The communication pipe is provided with a temperature sensor 9 for detecting a temperature in the generator and a pressure monitor 11 for detecting pressure in the communication pipe.