The present invention provides a technique that enables introduction of active ingredients, in particular, nucleic acids, into cells with superior efficiency; and cationic lipids, etc., for use in the technique. The compound or a salt thereof according to the present invention is a compound represented by formula (I) or a salt thereof. In formula (I), n represents an integer of 2 to 5, R represents a linear C1-5 alkyl group, a linear C7-11 alkenyl group, or a linear C11 alkadienyl group, and wavy lines each independently represent a cis-bond or a trans-bond.