A cationic lipid represented by the formula in the formula, R 1a and R 1b are each independently an alkylene group having 1 - 6 carbon atoms, X a and X b are each independently X 1, X 2 or X 3, wherein X 1 is represented by the formula: wherein R 5 is an alkyl group having 1 - 6 carbon atoms, wherein X 2 is represented by the formula: wherein p is 1 or 2, wherein X 3 is represented by the formula: wherein w is 1 or 2, R 2a and R 2b are each independently an alkylene group or an oxydialkylene group each having not more than 8 carbon atoms, Y a and Y b are each independently an ester bond, an amide bond, a carbamate bond, an ether bond or a urea bond, Z a and Z b are each independently Z 1: wherein s is an integer of 0 - 3, t is an integer of 0 - 3, u is an integer of 0 - 4, and R 4 in the number of u are each independently selected from an acetyl group, methoxycarbonyl group, methylcarbamoyl group, acetoxy group, acetamido group, methoxycarbonylamino group, fluorine atom, chlorine atom, bromine atom, iodine atom, methylsulfanyl group, phenylsulfonyl group, nitro group, trifluoromethyl group, cyano group, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, ureido group, methoxy group, ethoxy group, propoxy group, isopropoxy group, t-butoxy group, phenyl group, and phenoxy group and R 3a and R 3b are each independently a residue derived from a reaction product of a liposoluble vitamin having a hydroxyl group, and succinic anhydride or glutaric anhydride, or a residue derived from a reaction product of a sterol derivative having a hydroxyl group, and succinic anhydride or glutaric anhydride, or an aliphatic hydrocarbon group having 12 - 22 carbon atoms, wherein the liposoluble vitamin having a hydroxyl group is retinol, ergosterol, 7-dehydrocholesterol, calciferol, cholecalciferol, dihydroergocalciferol, dihydrotachysterol, tocopherol or tocotrienol, and wherein the sterol derivative having a hydroxyl group is cholesterol, cholestanol, stigmasterol, β-sitosterol, or lanosterol. R 1a and R 1b are each independently an alkylene group having 1 - 6 carbon atoms, X a and X b are each independently X 1, X 2 or X 3, wherein X 1 is represented by the formula: wherein R 5 is an alkyl group having 1 - 6 carbon atoms, wherein X 2 is represented by the formula: wherein p is 1 or 2, wherein X 3 is represented by the formula: wherein w is 1 or 2, wherein X 3 is represented by the formula: wherein w is 1 or 2, R 2a and R 2b are each independently an alkylene group or an oxydialkylene group each having not more than 8 carbon atoms, Y a and Y b are each independently an ester bond, an amide bond, a carbamate bond, an ether bond or a urea bond, Z a and Z b are each independently Z 1: wherein s is an integer of 0 - 3, t is an integer of 0 - 3, u is an integer of 0 - 4, and R 4 in the number of u are each independently selected from an acetyl group, methoxycarbonyl group, methylcarbamoyl group, acetoxy group, acetamido group, methoxycarbonylamino group, fluorine atom, chlorine atom, bromine atom, iodine atom, methylsulfanyl group, phenylsulfonyl group, nitro group, trifluoromethyl group, cyano group, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, ureido group, methoxy group, ethoxy group, propoxy group, isopropoxy group, t-butoxy group, phenyl group, and phenoxy group and R 3a and R 3b are each independently a residue derived from a reaction product of a liposoluble vitamin having a hydroxyl group, and succinic anhydride or glutaric anhydride, or a residue derived from a reaction product of a sterol derivative having a hydroxyl group, and succinic anhydride or glutaric anhydride, or an aliphatic hydrocarbon group having 12 - 22 carbon atoms, wherein the liposoluble vitamin having a hydroxyl group is retinol, ergosterol, 7-dehydrocholesterol, calciferol, cholecalciferol, dihydroergocalciferol, dihydrotachysterol, tocopherol or tocotrienol, and wherein the sterol derivative having a hydroxyl group is cholesterol, cholestanol, stigmasterol, β-sitosterol, or lanosterol.