CONCENTRATION RATIO CALCULATION METHOD FOR TWO-COMPONENT GAS AND CONCENTRATION CALCULATION METHOD FOR GAS TO BE DETECTED

[Problem] To provide a method for obtaining concentration of a gas to be detected with high precision, using two gas sensor elements. Also, to provide a method for obtaining a concentration ratio of a two-component gas, using a single gas sensor element. [Solution] A concentration ratio calculation method comprises: a first measurement step for heating a gas sensor element to a temperature at which both of two gas components introduced to the gas sensor element are reactive, maintaining the temperature for a predetermined amount of time, and measuring an electric resistance value at the gas sensor element; a second measurement step for heating the gas sensor element to a temperature at which only one of the two gas components is reactive, maintaining the temperature for a predetermined amount of time, and measuring an electric resistance value at the gas sensor element; and a concentration ratio calculation step for calculating a concentration ratio of the two gas components on the basis of a combination of t