To obtain a transgenic plant including a DNA sequence assigning a specific genetic information of a specific antigen of a pathogenic germ, the antigen or the like of which is capable of drawing out a secretory immune response after oral administration, and transduced with an antigen gene of a pathogenic germ.

The transgenic plant including the DNA sequence determining the gene information of the antigen of a pathogenic germ selected from a group comprising (A) colonization antigen, (B) virulence antigen, (C) an antigen determining group of the either, (D) a fusion protein comprising either antigen or their determining group, and expressing them, the antigen or their determining group of which is capable of drawing out a secretory immune response in human or other animals after oral administration, is obtained.