COMBUSTIBLE GAS DETECTOR

PROBLEM TO BE SOLVED: To detect presence of combustible gas of high concentration which is incapable of being detected by a catalytic combustion type gas sensor. SOLUTION: In the combustible gas detector, using the catalytic combustion type gas sensor 1 constituted by forming an oxidizing catalyst layer subjecting combustible gas to oxidative reaction to generate heat on the surface of a heater which generates heat by Joule heat due to energization, so as to form heat conduction relation, while keeping electric insulation, since sensor current changes with the elapse of time in a high concentration region, where the oxidation reaction of the oxidizing catalyst layer is impossible due to the thermal conductivity of the combustible gas being larger than that of air, and this change of the sensor current is detected by a measurement circuit 5.