Disclosed is an oral vaccine for a bacterium-induced infectious disease (e.g., typhoid fever, cholera, dysentery). The oral vaccine is a capsule preparation comprising an acid-resistant film and a transformed microorganism capable of expressing an antigen protein flagellin or secreting the flagellin out of the cell and encapsulated with the acid-resistant film. The microorganism may be an enterobacterium belonging to the genus Bifidobacterium, Lactobacillus, Lactococcus, or the like. The capsule preparation may have in any form selected from a seamless capsule preparation, a soft capsule preparation and a hard capsulepreparation.
