The present invention provides a gas sensor for detecting the gases at the high precision. The gas sensor is equipped with a first detection element which generates the resonance frequency variation because of the absorption of a specific gas and has a first oscillator of a specific structure and a first adsorption film provided on the first oscillator to absorb the above specific gas; a second detection element which has a second oscillator of the specific structure and a second adsorption film provided on the second oscillator to absorb the moisture and changes its resonance frequency according to the moisture of the above gas; a third detection element which has a third oscillator of a specific structure, and changes its resonance frequency according to the temperature of the gas; and acomputing 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 theresonance frequency of the third detection element.