The present invention relates to a double-stranded oligonucleotide
derivative, which contains two oligonucleotide derivatives each
containing at least one nucleotide derivative wherein a base portion of a
nucleotide is substituted with a metal coordination group that is
resistant to oxidation and metal atoms, wherein the double strands are
formed by coordination of each metal coordination group contained in each
oligonucleotide to a metal atom so as to form a complex.