A process of producing an immunogenic particle includes mixing an aqueous solvent A wherein an antigen(s) is/are dissolved and a water-immiscible organic solvent B wherein an amphiphilic polymer(s) whose hydrophobic segment(s) is/are poly(hydroxy acid) is/are dissolved, to form a reversed-phase emulsion； and removing the solvent from the reversed-phase emulsion to obtain an antigen-adjuvant microparticle complex, wherein the aqueous solvent A and/or the water-immiscible organic solvent B contains a surfactant.
