GAS SENSOR

PROBLEM TO BE SOLVED: To provide a gas sensor capable of preventing generation of a crack in a sensor element even if a light-off time for activating the sensor element is reduced and having a heater sintered separately from the sensor element. SOLUTION: This gas sensor is provided with a sheet-like sensor element formed of an oxygen ion conducting solid electrolyte body and having a space in its inside, and the sheet-like heater formed of insulating ceramics (in particular, alumina) and having a heating resistor. After the sensor element and the heater are separately baked, the heating resistor is so stacked as to be disposed close to the space of the sensor element, and the average resistance temperature coefficient of the heating resistor at 0-1,000 deg.C is 3,000 ppm/ deg.C or less (preferably 1,600 ppm/ deg.C).