A gas sensor is equipped with a first detection element which has a first oscillator and a first adsorption film provided on the first oscillator to adsorb a specific gas, and changes its resonance frequency according to the adsorption of the gas; a second detection element which has a second oscillator and a second adsorption film provided on the second oscillator to adsorb moisture in the gas, and changes its resonance frequency according to the adsorption of the moisture; a third detection element which has a third oscillator, and changes its resonance frequency according to the temperature of the gas; and a computing unit which corrects the change in the resonance frequency of the first detection element based on the change in the resonance frequency of the second detection element and the change in the resonance frequency of the third detection element.