Disclosed is a surfactant-like compound that can form a nucleic acid complex that has low toxicity to a living body, is easily transported to a target site with a small particle size, and has high expression efficiency at the target site. A hydrophilic group, a hydrophobic group, and 1 to 5 nitrogen-containing groups located between them, wherein the hydrophilic group is an ethylene glycol group represented by the following formula (1): The surfactant-like compound wherein the hydrophobic group is a linear or branched alkyl group having 1 to 18 carbon atoms or a cholesterol group, and the nitrogen-containing group is an amide group or an imidazolium group. R— (CH 2 —CH 2 —O) n— (1) (wherein n represents an integer of 40 to 120, R represents a hydrocarbon group having 1 to 18 carbon atoms) FIG. 10【課題】生体への毒性が低く、小粒子径で標的部位に移送され易く、標的部位での発現効率が高い核酸複合体を形成することができる界面活性剤様化合物を提供すること。【解決手段】親水性基と疎水性基とそれらの間に位置する１～５個の含窒素基とを具備し、 上記親水性基が下記式（１）で表されるエチレングリコール基であり、上記疎水性基が炭素数１～１８の直鎖又は分岐鎖のアルキル基又は、コレステロール基であり、上記含窒素基がアミド基又はイミダゾリウム基である界面活性剤様化合物。Ｒ－（ＣＨ２－ＣＨ２－Ｏ）ｎ－ ・・・・・（１）（式中、ｎは４０～１２０の整数を表す。Ｒは炭素数１～１８の炭化水素基を示す。）【選択図】図１０
