Nucleic acid complexes having at least one bulge structure

A nucleic acid complex having excellent target gene expression inhibitory effect, preferably to provide a double-stranded nucleic acid complex. A transcript, for example, the active portion comprising antisense nucleic acids complementary to the target gene transcript is complementary to the nucleic acid, and a carrier portion which comprises a nucleic acid having at least one bulge structure nucleic acid complex comprising, preferably by using a double-stranded nucleic acid complex, the problem is solved.