This work was on exploring an application of ion beam biotechnology in inducing rice mutants to combat blast disease infection and further analyzing the gene involved in the disease resistance. N-ion beam bombardment of rice seeds with ion energy of several tens of keV was applied to induce Thai local rice mutants possessing the high blast-disease resistance also with the high-yield character. The polymorphism in the fingerprint of the rice mutant compared with the wild-type was found. The gene which was related to phenotypic expression in the mutant and responsible for the resistance to the blast disease infection was identified to be linked to the Spotted leaf protein 11 (Spl11).