Chiral nucleic acid adjuvant having anti-allergic activity, and anti-allergic agent

Problem To provide a chiral nucleic acid adjuvant and anti-allergic agent having anti-allergic effect. Solution An adjuvant which comprises oligonucleotides which comprise two to four CpG motifs each represented by 5′-X 1 CpGX 2 -3′ and has a length of 14 to 32 nucleotides, wherein a nucleic acid at 3′ end side of at least two CpG motifs is connected by phosphorothioate linkage, wherein each nucleic acids at 3′ end and 5′ end of the oligonucleotide is S type nucleic acids connected by phosphorothioate linkage, and wherein the oligonucleotide comprises at least one nucleic acid without phosphorothioate modification. The present invention relates to an adjuvant comprising the oligonucleotide represented by the sequence number 67. The present invention relates to an anti-allergic agent comprising these adjuvant.