the method of detecting the hydrogen concentration by using a first heat - generating resistor of which a first electrophysical quantity varies depending upon the hydrogen concentration and a second heat - generating resistor which is neighboring said first heat - generating resistor in a direction of gas flow and of which a second electrophysical quantity varies depending upon the hydrogen concentration as does the first electrophysical quantity , to detect the concentration of hydrogen based on the first electrophysical quantity and the second electrophysical quantity , the method comprising : calculating the amount of change in a target physical quantity , which is either the first electrophysical quantity or the second electrophysical quantity , calculating the correction amount based on a difference between the first electrophysical quantity and the second electrophysical quantity , and a calculating the concentration of hydrogen based on a difference between the amount of change in the target physical quantity and the correction amount .