PURPOSE: A method for screening the pathogenic factors of rice blast disease is provided to offer a composition for preventing rice blast disease including an activity inhibitor or an expression inhibitor of 1,3-β-glucanosyl transferase as an active ingredient. CONSTITUTION: A method for screening the pathogenic factors of rice blast disease comprises following steps. A sample to be analyzed is contacted to a cell or tissue which includes a nucleotide sequence coding 1,3-β-glucanosyl transferase or 1,3-β-glucanosyl transferase. The activation amount or the expression amount of the 1,3-β-glucanosyl transferase is measured. The sample is determined as a rice blast controlling agent when the activation amount or the expression amount of the 1,3-β-glucanosyl transferase is reduced.
