Thistle is a perennial plant that is widely used for medicinal purposes. Information on the genetic diversity of thistle populations are great important for their conservation and germ plasmic utilization. Although thistle is an important medicinal plant species registered in South Korea, no molecular markers are currently available to distinguish them from other similar species from different countries. In this study, we developed single nucleotide polymorphism (SNP) markers derived from the nuclear ribosomal DNA internal transcribed spacer (ITS) regions of genomic sequences to identify distinct Korean-specific thistle species via an amplification refractory mutation system (ARMS)-PCR and high resolution melting (HRM) curve analyses. We performed molecular authentication of four different kinds of thistle species from different regions using DNA sequences in the ITS intergenic region. We also developed a quantitative PCR assay using species-specific ITS primers, which allowed us to estimate the ratio of Korean-specific thistle species using varying ratios of mixed genomic DNA templates from the two species. The SNP markers developed in this study are useful for rapidly identifying specific thistle species from different countries.