PROBLEM TO BE SOLVED: To provide a plant fermentation extract composition being a beverage having more prevention and amelioration effect on osteoporosis than isoflavone alone.SOLUTION: The plant fermentation extract composition comprises an extract that is obtained by fermenting an edible plant using a facultative anaerobic gram-negative bacterium living symbiotically in a plant and simultaneously culturing the facultative anaerobic gram-negative bacterium, and a plant isoflavone. The plant isoflavone may be a soybean isoflavone extract or a dairy product. The plant fermentation extract composition may comprise calcium, vitamin C, vitamin B, vitamin D and folic acid besides plant isoflavone.