This study was conducted to evaluate the anti-cancer activity of Fine Black ginseng (Panax ginseng Meyer, FBG BF) and its main component, Rg5, in MCF-7 (HER2-/ER+) breast cancer cells. Cell viability was determined by MTT assay. Action mechanisms were performed by cell cycle assay, Annexin V apoptosis assay and western blot analysis. FBG BF showed cytotoxicity in breast cancer cells in a dose-dependent manner. MTT assay showed that MCF-7 and MDA-MB-453 cell proliferations were inhibited by Rg5 treatment for 24, 48 and 72 hr in a dose-dependent manner.