A delivery method is provided which delivers a gene modifying tool which achieves a high gene modification efficiency in cells. This composition, for inducing genetic modification in a target locus in a cell, contains 1) the compound represented by expression (I) or a salt thereof, 2) structural lipids, and 3) guide RNA or DNA containing a sequence encoding this, and/or RNA-guided nuclease, or nucleic acids including a sequence encoding this. In expression (I), n is an integer 2-5, R is a linear C