The present study was performed to investigate whether Achyranthes Radix extracts play roles in the bone metabolism. Three kinds of Achyranthes Radix extracts (methylene chloride (MC), ethylacetate (Ea), and water (W)) were used for bioassay. We examined cellular activities of osteoblasts by measurement of cell proliferation rate, alkaline phosphatase (ALP) activity, and calcified nodule formation. Osteoclast generation was assayed by measuring the number of tartrate-resistant acid phosphatase (TRAP) (+) multinucleated cells after culture of osteoclast precursor cells. There was a maximum 20% increase in proliferation rate of osteoblastic cells after treatment with MC. First and second subfraction of MC layer increased proliferation of osteoblast. Ea layer and second subfraction of MC layer increased ALP activity. Also MC layer and second subfraction of MC layer from Achyranthes Radix extracts increased the calcified nodule. MC layer and second subfraction of MC layer from Achyranthes Radix extracts significantly decreased in the number of TRAP (+) multinucleated cells. Taken together, Achyranthes Radix stimulates the proliferation and bioactivities of bone-forming osteoblasts, and inhibits activities of bone-resorbing osteoclasts