Recently, polymerase chain reaction (PCR)-based methods have been used to reclassify Ureaplasma urealyticum into two independent species (spp.), designating U. parvum and U. urealyticum. In the current study, we aim to reclassify U. urealyticum and to analyze the correlation between the presence of a genetic marker and an antibiotic resistance of U. urealyticum. Susceptibility test against tetracycline, levofloxain or moxifloxacin was performed by broth microdilution method. The presence of tet(M) gene and the mutations of quinolone resistance-determining regions (QRDRs) were analyzed by PCR and sequencing. Among fourteen Ureaplasma isolates, three were identified as U. parvum and eleven were identified as U. urealyticum, and this is first report showing that two independent spp. of U. urealyticum isolated from Korean are present. The minimum inhibitory concentration (MIC) ranges for Ureaplasma isolates were as follows: tetracycline 0.25~128 ${mu}g/ml$, levofloxacin 1~8 ${mu}g/ml$, and moxifloxacin 0.5~4 ${mu}g/ml$. The tet(M) determinant was found in 3 among 14 Ureaplasma isolates with tetracycline MIC of >16 ${mu}g/ml$, suggesting that the presence of the tet(M) determinant is associated with tetracycline resistance. Mutations of gyrA, gyrB, parC, and parE genes in the QRDRs were found in 3 among 14 Ureaplasma isolates, exhibiting only parE gene mutation is associated with fluoroquinolone resistance.