An electric field variable gas sensor includes a semiconductor substrate, an insulating film disposed on the semiconductor substrate, a semiconductor thin film material disposed on a part of the semiconductor substrate and a part of the insulating film, a gas molecule adsorption inducing material disposed on the semiconductor thin film material, a first electrode disposed on the semiconductor substrate to be spaced apart from the semiconductor thin film material, and a second electrode disposed on the insulating film to be connected with the semiconductor thin film material.