The present invention relates to a chemical detection method using a semiconductor type gas sensor, an electrode unit 110 and the semiconductor type gas sensor (100 is configured to include a detection unit 120, and electrically connected to the electrode 110 ) a method for determining the type and concentration of the target gas (target gas) by using a, (I) a step of preparing the semiconductor type gas sensor (100); (II) the step of adsorption to the detection section 120 to the target gas (target gas); (III) applying a voltage to the electrode unit 110; (IV) measuring the impedance of the target gas (target gas) is adsorbed detection unit 120; (V) phase which is added in the derived real and imaginary impedance; And (VI) the target gas (target gas) is the impedance relationship between the real and imaginary parts of the absorption detection unit 120 are recorded at different concentrations of the target gas (target gas) 2 based on the data 420, It is made by a step for deciding the type and concentration of the target gas (target gas) against parts of the impedance real and imaginary of the relief in the (V) stage, the power is the target gas, characterized in that Exhibition causes ( It provides a method for determining the type and concentration of the target gas).