Introduction. Antimicrobial resistance (AMR) among Mycoplasma genitalium is a global issue. Understanding the transmission dynamics of infection is an important factor in reducing the occurrence of AMR. Hypothesis/Gap Statement. There is limited information on the genotyping and AMR traits of M. genitalium . Aims. Single-locus sequence-based (SLSB) mgpB sequence typing and genetic diversity analyses of AMR M. genitalium isolated from patients in the Republic of Korea were performed to clarify the transmission dynamics and eludicate proper management. Methodology. Sanger sequencing of mgpB, 23S rRNA, parC and gyrA genes from a total of 103 M . genitalium -positive specimens from 89 patients was carried out. Results. Twenty-seven different mgpB genotypes (GTs) were identified; 12 had been reported previously and 15 had not. GT7 and GT8 occurred frequently (n=38, 36.89 %, and n=16, 15.53 %, respectively). The genetic diversity of the AMR-determining sites was randomly dispersed among the different GTs. However, these GTs were classified into two phylogenetically distinct clusters that were significantly correlated with patient age and genetic diversity at positions 2058 and 2059 in the 23S rRNA gene. The GTs of 20 consecutive samples from 6 patients were compared to investigate temporal changes in GTs. One specimen changed its GT during follow-up, suggesting a new infection. Conclusions. mgpB sequence typing can be a reliable tool for epidemiological studies. Two clusters have different characteristics in terms of genetic diversity. The cluster with genetic diversity in the AMR-determining site may be explained by the high prevalence of the specimens and subsequent antimicrobial exposure during the study period.