The invention provides a method of modifying a targeted site of gram-positive bacterium of a double stranded DNA. The method includes contacting the double-stranded DNA with a complex of a nucleic acid sequence-recognizing module that specifically binds to a target nucleotide sequence in a given double stranded DNA and a nucleic acid base converting enzyme to convert, delete, or insert one or more nucleotides in the targeted site without cleaving at least one strand of the double stranded DNA in the targeted site, by introducing the nucleic acid encoding the complex into the gram-positive bacterium. The invention also provide a nucleic acid-modifying enzyme complex of a nucleic acid sequence-recognizing module that specifically binds to a target nucleotide sequence in a double stranded DNA of a gram-positive bacterium and a nucleic acid base converting enzyme bonded to each other, which complex is used for the method.