PROBLEM TO BE SOLVED: To provide a method for using a gene and a gene product, including preservability of Lentinus edodes, by specifying a gene influencing the preservability of Lentinus edodes fungus. SOLUTION: A Lentinus edodes fungus having more improved preservability than that of a parent strain is prepared by specifically controlling the expression of a cell-wall degrading enzyme-associated gene (chitinase, glucanase, etc.) of Lentinus edodes fungus having a specific base sequence. A protoplast of filamentous fungus is prepared by using the gene product. COPYRIGHT: (C)2008,JPO&INPIT