PROBLEM TO BE SOLVED: To provide an antimicrobial agent which suppresses proliferation of Streptococcus mutans and Streptococcus sobrinus considered as causative microorganisms of decayed tooth (dental caries) which is an oral cavity disease, Actinomyces viscosus, Porphyromonas gingivalis and Fusobacterium nucleatum considered as causative microorganisms of periodontal disease, Streptococcus pyogenes being a hemolytic streptococcus as pathogenic bacteria of inflammatory diseases, Staphylococcus aureus as causative microorganisms of food poisoning and to provide a composition for oral cavity and food and drink products.SOLUTION: By including, as an effective ingredient, water and/or an organic solvent extract of one or two kinds of ascomycetes or basidiomycetes selected from Pholiota nameko, Pleurotus ostreatus, Hericium erinaceum, Macrocybe gigantea Massee, Ganoderma neojaponicum Imazeki, an antimicrobial agent against oral cabity diseases, streptococcal diseases and Staphylococcus aureus can be obtained and also a composition for oral cavity and food and drink products containing the same can be obtained.
