The present invention provides a nucleic acid complex with low toxicity and high safety that can persistently maintain a nucleic acid, such as siRNA or the like, in a cell and a nucleic acid delivery composition that can efficiently deliver the nucleic acid complex into a cell. A nucleic acid complex with low toxicity and high safety that can persistently maintain a nucleic acid in a cell can be obtained by forming a complex using a nucleic acid to be introduced into a cell, and a highly branched cyclic dextrin. Moreover, when a carrier comprising (A) a diacylphosphatidylcholine, (B) cholesterol and/or a derivative thereof, and (C) an aliphatic primary amine is used as a nucleic acid delivery carrier to introduce the nucleic acid complex into a cell, the safety, the efftciency of intracellular delivery, and the persistence of the nucleic acid in the cell can be further improved.本發明提供一種具有低毒性及高安全性的核酸複合物,其可在細胞中持續維持核酸(諸如,siRNA或其類似物);及一種可將該核酸複合物有效率地輸送進入細胞中之核醃輸送組成物。該具有低毒性及高安全性、可在細胞中持續維持核酸的核酸複合物,可藉由使用欲引進細胞的核酸與一高分枝環狀糊精來形成一複合物而獲得。再者,當使用一包含(A)二醯基磷脂醯膽鹼、(B)膽固醇及/或其衍生物、及(C)脂肪族一級胺之載體作為核酸輸送載體來將該核酸複合物引進細胞中時,可進一步改良該核酸在細胞中的安全性、細胞內輸送效率及持續性。
