MRSA generates organic acids by metabolizing carbohydrates. To investigate whether the ethanol extract of A. princeps can suppress organic acid production in MRSA, the ethanol extract of A. princeps was added to MRSA culture medium and the change in pH was measured. The pH of the control culture medium was approximately 7.2 before the incubation, which decreased to approximately 5.87 after culturing (Table 2). However, this decrease in pH was suppressed in the group treated with the ethanol extract of A. princeps (1–8 mg/mL). The positive control, 0.1% NaF, also showed suppression in pH reduction. These results reveal that organic acid production in MRSA can be inhibited by the ethanol extract of A. princeps.