Fuente: WIPO "tomato" The purpose of the present invention is to provide a technology for, by using a small number of gRNA or crRNA, simultaneously editing numerous genes that are functionally duplicated. It was found that a CasΦ protein derived from huge phages can cut a target sequence having a nucleotide length of 16 or more, and a mismatch sequence including a mismatch of 1 or 2 bases with respect to the target sequence. Accordingly, provided is a genome editing method that is for duplicated genes and that uses said CasΦ protein.