GAS DETECTOR

PROBLEM TO BE SOLVED: To accurately detect an inflammable gas concentration without being affected by miscellaneous gas existing in a measuring atmosphere, and to provide high detection precision. SOLUTION: This gas detector is a detector for detecting an inflammable gas concentration generated in a measured chamber A, a residual oxygen concentration inside the measured chamber A is measured by the first oxygen sensor part 2 of a limiting current type having a pair of electrodes 22, 23 in both faces of a zirconia substrate 21 of an oxide ion conductive solid electrolyte, after the inflammable gas generated reacts with oxygen in atmospheric gas, and an oxygen concentration in an outside space D where the atmospheric gas introduced into the chamber A exists is measured, on the other hand, by the second oxygen sensor part 3 of a limiting current type having a pair of electrodes 32, 33 in both faces of a zirconia substrate 31. Since gas components.concentrations excepting the inflammable gas are the same in the gas in the chamber A and the gas in the space D, influences caused by the miscellaneous gas components such as a steam containned in the atmospheric gas are corrected based on a detection result by the second oxygen sensor part 3 so as to accurately detect the inflammable gas concentration.