The immunogenic composition comprises, as active ingredients, immunogenic particles obtained from antigen-adjuvant microparticle complexes wherein the antigen is enclosed in adjuvant microparticles obtained from an amphiphilic polymer having a poly(hydroxy acid) for the hydrophobic segments, and a surfactant. The immunogenic composition obtained by the surfactant being enclosed in the immunogenic microparticles has an excellent ability to activate immunity in vivo even with small amounts of antigen and few immunizations.
