To produce a high-performance specific gene amplification primer for detecting, quantifying, or identifying Vibrio vulnificus, having low risk of misidentification and practically sufficient amplification efficiency and amplification specificity. We have determined partial nucleotide sequences of gyrB, rpoD, and recA genes of Vibrio vulnificus and the closely related species, revealed their phylogenetic relationship, and then identified nucleotides characteristic to Vibrio vulnificus. Thus, we have made it possible to design a probe having high specificity and a gene amplification primer having high specificity and excellent amplification efficiency, both of which contain the characteristic nucleotides.