PROBLEM TO BE SOLVED: To more promote the utilization of plum vinegar produced as a by-product on production of a plum processed food, further, to provide a safe antimicrobial agent which has strong antimicrobial activity, and to provide pharmaceuticals, quasi-pharmaceuticals, cosmetics, foods and feeds having strong antimicrobial activity.SOLUTION: The antimicrobial agent includes plum vinegar polyphenol prepared from plum vinegar, a plum vinegar polyphenol hydrolyzate obtained by hydrolyzing plum vinegar polyphenol or plum vinegar polyphenol aglycone as the constituent of plum vinegar polyphenol, and has high antimicrobial activity and safety. Further, the pharmaceuticals, quasi-pharmaceuticals, cosmetics, foods and feeds include the antimicrobial agent.
