This invention provides a method for knock-in of a donor DNA into the genome of a cell, comprising introducing at least one artificial nuclease system capable of cleaving target sequence(s) of the cell genome, the donor DNA, and two single-stranded oligonucleotides (ssODNs) into the cell, the artificial nuclease system cleaving the target sequence(s) on the cell genome, the two ssODNs each complementary to one of the ends generated by the target sequence cleavage in the cell genome and to one of the introduction ends of the donor DNA, the donor DNA being knocked-in at the cleavage site via the two ssODNs.