Nucleic acid peptides (NAPs) with a mimetic amino acid side residue at the base position of the nucleotide via an amide bond were synthesized from 3-deoxy-6-O-(4,4-dimethoxytrityl)allonic acid methyl ester as the common precursor. Furthermore, an NAP with an octapeptide at the Cl' position was synthesized. The peptide-linked NAP exhibits both functions of the oligopeptide part and of the oligonucleotide part.