The inhibitor of Hepatitis B virus and HIV activity according to the present invention comprises a Lentinus edodes mycelium extract obtained by the steps of inoculating Lentinus edodes fungus in a solid culture medium comprising bagasse, then disentangling the solid culture medium containing the proliferated mycelium, adding water and at least one enzyme selected from a group consisting of cellulase, protease and glucosidase to the disentangled solid culture medium with keeping the solid culture medium at 30 to 50° C., grinding and milling the solid culture medium in the presence of the enzyme to obtain a Lentinus edodes mycelium extract, and then heating the extract to a temperature of not higher than 95° C. to inactivate the enzyme and sterilize the extract.