These results suggested that EJT extract treatment had anti-inflammatory effects through inhibition of activation of p38 and NF-κB. Therefore, we suggested that E. japonicum extract can be used as a therapeutic agent for RA treatment owing to its anti-inflammatory effects; however, it is necessary to elucidate the mechanism of NF-κB and p38 inhibition to solve the problems in the development of such therapeutic agents. The gene discussed is NFKB1; the disease is rheumatoid arthritis.