GAS DETECTOR

PROBLEM TO BE SOLVED: To provide a gas detector capable of shortening the time required for gas detection in a low-temperature period.SOLUTION: A heater control unit 31 controls a thermal dose of a heater 21 to alternately provide a high-temperature period and a low-temperature period in which a detection object gas is to be detected. A sampling unit 32 samples a resistance value Rs of a gas sensitive part 20 with a period shorter than the low-temperature period, in the low-temperature period. A hold unit 33 holds a resistance value sampled by the sampling unit 32 at the end time of a previous low-temperature period, as a hold value. The hold unit 33 compares a resistance value sampled by the sampling unit in a current low-temperature period, with the hold value and holds smaller one of them as a new hold value and holds a resistance value sampled by the sampling unit 32 at the end time of the current low-temperature period, as the hold value. A gas determination unit 34 successively compares the hold value in the hold unit 33 with a prescribed gas determination level to determine whether the detection object gas exists or not.