The present invention provides a novel donor polynucleotide formed by connecting both ends of a genome fragment including a cleavable site, with a polynucleotide including a positive selection marker gene and a negative selection marker gene. The use of said donor polynucleotide enables cleavage to be performed in a homologous site of the donor polynucleotide without performing cleavage in a target gene locus, and as result thereof, it is possible to modify only the target gene while avoiding the possibility of "off-target," that is, the sequence other than the target sequence being modified.
