Objectives : Aconiti Lateralis Preparata Radix (Aconitum Carmichaeli, AC) and Cinnamomi Cortex (Cinnamomi Cortex, CC) have been treated to elderly for kidney yang enhancement in Korean traditional medicine. In this study, the effects of water extract of AC and CC on RANKL (Receptor Activator for Nuclear Factor ${kappa}B$ Ligand)-induced osteoclast differentiation were evaluated in culture system. Methods : MTT assay was used to evaluate the potential cytotoxicity of AC and CC extracts in bone macrophage marrows (BMMs) stimulated with M-CSF. TRAP (tartrate-resistant acid phosphatase) staining and TRAP activity were performed to know the inhibitory effect on osteoclast differentiation. The protein expression levels of nuclear factors such as activated T cell(NFAT)c1, c-Fos, MAPKs and ${eta}$-actin in cell lysates treated with AC and CC extracts were analysed by western blotting. Results : AC, CC extracts and their co-administration inhibited significantly RANKL-induced osteoclast differentiation in BMMs in a dose dependent manner without toxicity. Each AC and CC extracts inhibited the phosphorylation of p38. Also, AC and CC extracts, respectively, inhibited the protein expression of c-Fos and NFATc1 more than Co-administration of AC and CC even if all treatments did. It was observed that RANKL-induced degradation of I-${kappa}B$ is significantly suppressed by all treatments. Conclusions : Taken together, It was concluded that AC and CC have beneficial effect on osteoporosis by inhibition of osteoclast differentiation. Thus, Atractylodis AC and CC could be a treatment option for osteoporosis.