Tricholoma matsutake is a commercially valuable fungus that produces gourmet mushrooms. The artificial cultivation method that is currently used to produce fruiting bodies involves the transplantation of pine trees infected with T. matsutake from their natural habitats and the successful infection of young pine trees and mushroom production have been reported in Hongcheon. In this study, T. matsutake genetic diversity and relationships in this region were investigated. A genotype analysis was conducted on 25 fruiting bodies collected from an area approximately 2.56 km2 in size using 10 simple sequence repeat (SSR) markers. The analysis revealed 25 genotypes and 23 alleles with mean observed (HO) and expected (HE) heterozygosities of 0.312 and 0.293, respectively. The average polymorphism information content (PIC), which indicates marker polymorphism, was 0.257. A phylogenetic analysis showed no clear correlation between collection location and genetic distance; a spatial autocorrelation analysis indicated no significant genetic structure within 1600 m; and the Mantel test showed no significant correlation between genetic and geographic distances. These results were consistent with previous reports on Japanese populations. This study provides insights into the genetic diversity and structure of T. matsutake at a local scale and highlights the need for further studies across broader geographical ranges.