Cationic lipid having cystine skeleton

A cationic lipid represented by the formula (1):

• wherein
• L1a and L1b are each independently an amide bond, a carbamate bond, or a urea bond,
• R1a and R1b are each independently an alkylene group having not more than 8 carbon atoms or an oxydialkylene group having not more than 8 carbon atoms,
• ka and kb are each independently 0 or 1,
• Xa and Xb are each independently a dialkylamino group having two alkyl groups each independently having 1 to 5 carbon atoms, or a 3- to 6-membered cyclic amino group,
• L4a and L4b are each independently an ester bond or an amide bond,
• R2a and R2b are each independently an alkylene group having not more than 8 carbon atoms or an oxydialkylene group having not more than 8 carbon atoms,
• L2a and L2b are each independently an ester bond, an amide bond, a carbamate bond, an ether bond, or a urea bond,
• ma and mb are each independently 0 or 1,
• R3a and R3b are each independently a divalent group derived from an aromatic compound having 3 to 16 carbon atoms and at least one aromatic ring, and optionally having
• a hetero atom,
• L3a and L3b are each independently an ester bond, an amide bond, a carbamate bond, an ether bond, or a urea bond,
• na and nb are each independently 0 or 1,
• R4a and R4b are each independently an aliphatic hydrocarbon group having 12 to 22 carbon atoms, or R5—CO—(CH2)p—,
• R5 is a residue of a liposoluble vitamin having a hydroxy group or a residue of a sterol derivative having a hydroxy group, and
• p is 2 or 3.