The present invention provides a cationic lipid represented by formula (I) (in the formula, R1 and R2 are C8-24 alkyl groups or the like, R3 is a hydrogen atom, C1-3 alkyl group, formula (A) (in the formula, R4 and R5 are hydrogen atoms or the like, n3 is an integer of 2-6), or formula (B) (in the formula, R6 and R7 are hydrogen atoms or the like, n4 is an integer of 1-6), n1 is an integer of 0-4, n2 is an integer of 1-4 (however, cases when n1 is 0 and n2 is 1 are excluded)), and compositions and the like containing this cationic lipid and nucleic acid.本發明提供一種下述式(I)所表示之陽離子性脂質、以及含有該陽離子性脂質及核酸之組合物等，[式中，R1及R2為碳數8~24之烷基等，R3為氫原子、碳數1~3之烷基、式(A)(式中，R4及R5為氫原子等，n3為2~6之整數)、或式(B)(式中，R6及R7為氫原子等，n4為1~6之整數)，n1為0~4之整數，n2為1~4之整數(其中，n1為0且n2為1之情形除外)]。
