Abstract: Disclosed is a specific identification method of an MRSA and MRC-NS, which is speedy, simple and reliable. Specifically, the present invention provides a diagnostic method of an MRSA or MRC-NS, which comprises performing a reaction with a sample by making combined use of a part of a mecDNA, which is an integrated adventitious DNA existing on a chromosome of the MRSA or MRC-NS and carrying an mecA gene thereon, and a part of a nucleotide sequence of a chromosomal DNA surrounding the integrated DNA; and also a diagnostic method of an MRSA or MRC-NS by PCR, LCR or hybridization, which comprises performing a reaction with a sample by using a nucleotide sequence of a chromosomal DNA surrounding an integrated site of a mecDNA in a chromosome of an MSSA or MSC-NS, wherein said method makes use of an occurrence of a negative reaction when said sample contains a mecDNA integrated therein.