Metronidazole (MTZ) is an important antimicrobial agent in anaerobic infections and is widely used in clinical settings. The rate of MTZ resistance in anaerobic bacteria has been increasing in recent years, and the nim gene (nitro-imidazole reductase) is one of the resistance mechanisms. Prevotella bivia is found in humans in the urinary tract and vagina and is known to cause infections in some cases. One of the nim genes, nimK, has recently been discovered in this species of bacteria, but there are no reports of antimicrobial resistance (AMR)-related regions in its whole genome level. In this study, we analyzed the AMR region of nimK-positive P. bivia derived from clinical specimens based on comparisons with other anaerobic genomes. P. bivia was found to be engaged in horizontal gene transfer with other anaerobic bacteria, and the future spread of the nimK gene is a concern.