Bone maintains its homeostasis through balance between bone resorbing osteoclasts and bone forming osteoblasts. Thus, unusual balance between osteoclasts and osteoblasts leads to pathological bone diseases, such as osteoporosis, rheumatoid arthritis, autoimmune arthritis, periodontitis. Schisandra chinensis well known traditional herbal has been used for treatment of diseases in China, Korea, Japan, andothers. Recently, research studies have demonstrated that the lignans found in Schisandra chinensis stimulate osteoblasts and suggest that it may be helpful against osteoporosis. However, the inhibitory effect of water extract of Schisandra chinensis on osteoclast differentiation remains largely unknown. In this study, Water extract of Schisandra chinensis markedly suppressed RANKL-induced osteoclast differentiation in cultures of BMMs without cytotoxicity. The mRNA expression of c-Fos, NFATc1, and TRAP induced by RANKL was inhibited by water extract of Schisandra chinensis. It also suppressed c-Fos and NFATc1 protein expression. Taken together, these results suggest that water extract of Schisandra chinensis has the potential to serve as a treatment of bone disease such as osteoporosis.