The present invention provides a cationic lipid which is able to be used fornucleic aciddelivery to the cytoplasm. A cationic lipid according to the present inventionis, forexample, a compound represented by formula (1a) or a pharmaceuticallyacceptable saltthereof. (In formula (1a), each of L1 and L2 independently represent analkylene grouphaving 3-10 carbon atoms； each of R1 and R2 independently represent an alkylgrouphaving 4-22 carbon atoms or an alkenyl group having 4-22 carbon atoms； X1represents a single bond or -CO-O-； and ring P represents one of formulae (P-1) to(P-5).)(In formulae (P-1) to (P-5), R3 represents an alkyl group having 1-3carbon atoms.)(see formula 1a,)(see formula P-1)(see formula P-2)(see formula P-3)(see formula P-4)(seeformula P-5)
