The method for producing a surface enhanced infrared absorption sensor of the invention is characterized by: adsorbing metallic nanoparticles dispersed in a solution on a surface of a substrate, or allowing the adsorbed metallic nanoparticles to be grown in a solution, thereby forming a film; applying infrared light to the substrate from the side thereof opposite to the side on which the metallic nano-thin film is disposed; detecting evanescent waves exuding from the substrate; and regulating a surface enhanced infrared adsorption activity while monitoring surface enhanced infrared adsorption signals in situ, whereby the metallic nano-thin film is grown in the form of flat and discontinuous islands. According to the method, there is provided a production technique for a surface enhanced infrared absorption (SEIRA) sensor having a higher sensitivity and more excellent in the reproducibility.