The antibacterial activity of materials derived from the rhizome of Alpinia officinarum (Zingiberaceae) against Helicobacter pylori ATCC 43504, ATCC 700392, and ATCC 700824 was examined using paper-disc diffusion and agar dilution methods. Results were compared with those following treatment with currently used antibiotics: amoxicillin, metronidazole, and tetracycline. The bioactive principle was characterized as the diarylheptanoid 5-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-heptanone by spectroscopic analysis. This compound was isolated from A. officinarum leaves as a new anti-H. pylori principle. Against H. pylori ATCC 43504, ATCC 700392, and ATCC 700824, the antibacterial activity of the diarylheptanoid (48, 24, and $24{mu}g$/mL) was comparable to that of metronidazole (32, 16, and $16{mu}g$/mL) but less effective than that of either amoxicillin (0.06, 0.06, and $0.03{mu}g$/mL) or tetracycline (0.5, 1, and $0.5{mu}g$/mL), based on minimum inhibitory concentrations. A. officinarum rhizome-derived materials, particularly the diarylheptanoid isolated, merit further study as potential antibacterial functional food products or therapeutic products for prevention or eradication from humans from diseases caused by H. pylori.