T o provide: a bactericidal agent which utilizes a bactericidal acnvity and a pnarmacologicai activnv o i a plant belonging t o the family Juncaceae^ comprises a material produced b y seeding a seed mushroom mycelium t o a plant belonging t o the family Juncaceae^ culturing the mycelium while adding a nutrient source t o thereby proliferate the mycelium and then drying the proliferated mycelium, can exhibit an excellent bactericidal activity even when used in a small amount, can b e added t o a food, can b e sprayed onto an agricultural crop or soil, and can b e used as a therapeutic agent for athlete"s foot and a method for producing the bactericidal agent. [Solution] A plant belonging t o the family Juncaceae whicn i s cut into a predetermined length or wmch i s cut into a predetermined length and then milled i s mixed with a nutrient source for a seed mushroom mycelium, and the seed mycelium i s seeded t o the mixture o f the plant belonging t o the family Juncaceae and the nutrient source and then cultured at a growth temper ature for the seed mycelium for a predetermined time period.
