To prevent and treat the osteoporotic fracture, more attention should be paid in old age patients. Osteoclast which has ability to bone resorption is originated from hematopoietic cell line and plays a key role osteoporotic bone loss. Rubi Fructus has been widely used in Oriental medicine. Extracts of the leaves and fruit of Rubus species have been used in various countries as natural remedies to treat diabetes, infections, colic, and burns. However, the effect of extract of Rubi Fructus (fruit of Rubus coreanus Miq.) in osteoclast differentiation remains unknown. Thus, we evaluated the effect of Rubi Fructus on receptor activator of nuclear factor-kB ligand (RANKL)-induced osteoclast differentiation. Here we found that Rubi Fructus significantly inhibited osteoclast differentiation induced by RANKL. Rubi Fructus suppressed the activation of p38 pathway and NFkB in bone marrow macrophages (BMMs) treated with RANKL. Also, Rubi Fructus significantly inhibited the mRNA expression of c-Fos, tartrate-resistant acid phosphatase (TRAP), osteoclast-associated receptor (OSCAR), nuclear factor of activated T cells (NFAT)c1 and cathepsin K in BMMs treated with RANKL. Particularly, Rubi Fructus greatly inhibited the protein expression of c-fos and NFATc1. especially in the case of NFATc1 expression, a master transcription factor of the differentiation of osteoclasts is very important step for osteoclastogenesis. Taken together, our results demonstrated that Rubi Fructus may be useful treatment option of bone-related disease such as osteoporosis and rheumatoid arthritis.