The present invention relates to a novel biomarker for predicting sensitivity to an MET inhibitor, and a use thereof, and more specifically, the present invention provides: a biomarker for predicting sensitivity to the MET inhibitor, the biomarker comprising the Immunoglobulin Superfamily member 1 (IGSF1, NM_001555.2) gene; a composition for predicting sensitivity to the MET inhibitor, the composition comprising a pharmaceutical preparation for measuring the degree of expression of the gene in the biomarker, or the degree of expression of the protein of the gene; a pharmaceutical composition for treating diseases related to the dysregulation of the MET signaling pathway, the pharmaceutical composition comprising, as an active ingredient, an inhibitor inhibiting the expression of the gene in the biomarker, or the expression or activity of the protein of the gene; a kit for predicting sensitivity to the MET inhibitor, the kit comprising the compositions; and a method for predicting sensitivity to the MET inhibitor. According to the present invention, the present invention has an excellent effect of predicting sensitivity to the MET inhibitor for stomach cancer or lung cancer, and thus the present invention may be usefully employed for treating stomach cancer or lung cancer.