Periodontitis is one of the most common diseases associated with the lifestyle habits of adults and is caused by the formation of biofilms, called dental plaques, in periodontal pockets by oral bacteria, such as Porphyromonas gingivalis. Bangle, Zingiber purpureum Rosc. (Indonesian ginger), a native Indonesian plant, has been traditionally consumed as food and medicine across Southeast Asia. The cis- and trans-banglenes, components of the rhizomes of Z. purpureum, have been reported to possess neurotrophic activity. Hexane extract of bangle exhibited antibacterial activity against P. gingivalis, with a minimum inhibitory concentration of 8 μg/mL. We isolated several compounds from the active fractions through the bioassay-guided isolation of hexane extract. Further, we found that c- and t-banglene inhibited the growth of P. gingivalis at 4 µg/mL; however, these compounds showed no antibacterial effects against oral microorganisms. We also observed that c- and t-banglenes resulted in 47% and 40% reductions in biofilm formation. In conclusion, our results suggest that banglene has specific antibacterial effects against the periodontopathogen P. gingivalis, with minimal impact on oral microorganisms. Thus, banglene has potential applications in the prevention of periodontitis without the risk of substituted microbisms.