beta-Glucan schizophyllan (SPG) and CpG oligonucleotides (ODNs) can form a complex (denoted by CpG-dA(40)/SPG), which drastically induces immune-response owing to a combination of immunocyte-targeting delivery due to SPG and immunostimulative CpG ODN. We crosslinked CpG-dA(40)/SPG by adding cCpG-dA(40)/SPG to obtain larger particles than the original one by using cCpG-CpG hybridization, where cCpG denotes the complementary sequence of CpG. The crosslink particles showed higher immune stimulation and can thus be used as a more potent vaccine adjuvant than CpG-dA(40)/SPG itself.