To investigate the effects of iota-carrageenan (CAR) and/or alum on the adjuvancity as well as the structural difference of oligosaccharide on the IgG2b in the adjuvant effect, C57BL/6 mice were immunized twice with fetuin as a model antigen. CAR alone showed no significant effect on induction of antibody except IgG1. In contrast, Alum-CAR (after mixing of antigen-Alum, CAR adjuvant was prepared) and CAR-Alum (after formulation of antigen-CAR, Alum adjuvant was prepared) enhanced production of antibody, especially, IgG2b. After separation of IgG2b, changes of glycosylation were investigated using enzymelinked lectin assay. High affinity of IgG2b to N-acetylneuraminic acid, galactose and mannose-specific lectin were induced by CAR-Alum adjuvant, however, the affinity of IgG2b induced by CAR-Alum to GlcNAc and GalNAc-specific lectin were much less than that induced by Alum-CAR.