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 EFFICIENCY OF INTRACELLULAR DELIVERY, AND THE PERSISTENCE OF THE NUCLEIC ACID IN THE CELL CAN BE FURTHER IMPROVED.
