A novel vaccine effective in fish infections caused by Edwardsiella tarda, and a method for preventing fish infections are provided. More particularly, the invention relates to a vaccine against fish infections caused by Edwardsiella tarda, containing an antigen derived from Edwardsiella tarda which does not practically exhibit pathogenicity against fish to be administered. Further, the invention relates to a method for producing the vaccine against fish infections caused by Edwardsiella tarda, characterized by using Edwardsiella tarda which does not practically exhibit pathogenicity against fish to be administered. Further, the method for preventing fish infections of the invention includes the step of administering the vaccine of the invention to fish.
