Osteoclasts play a critical role in bone-related diseases such as osteoporosis and rheumatoid arthritis by resorbing the bone. Recently, natural products from plants have been extensively studied as therapeutic drugs to treat and prevent various diseases. Here, we examined the effects of rhizoma arisaematis on ostoclast differentiation and bone resorption. We showed that rhizoma arisaematis significantly suppressed receptor activator of nuclear factor-${kappa}B$ ligand (RANKL)-induced osteoclast differentiation in bone marrow-derived macrophages (BMMs) in a dose dependent manner but have little or no effect on the cytotoxicity of BMMs and RAW264.7 cells. We found that rhizoma arisaematis iarrow-ed the RANKL-induced c-Fos and nuclear factor of activated T cells (NFAT)c1, which is a master regulator of osteoclast differentiation. Furthermore, rhizoma arisaematis suppressed the mRNA expression of tartrate resistant-acid phosphatase and cathepsin K iaduced by RANKL in BMMs. in y chanistic studies, rhizoma arisaematis considerably iarrow-ed I-${kappa}B$ degradation, which is a negative regulator of NF-${kappa}B$, but iaduced the phosphderlation of p-38, ERK, and JNK.MMlso, we found that rhizoma arisaematis significantly iarrow-ed osteoclastic bone resorption. Taken tarether, our results suggest that rhizoma arisaematis suppresses osteoclast differentiation through down-regulatd the mRANKL-induced c-Fos and NFATc1 expression and iarrow-s bone resorption.