This study was carried out to know the immunological effect of GDGT on CIA(collagen induced arthritis) mice, a model of rheumatoid arthritis. For this purpose, GDGT was orally administerd to mice with arthritis induced by collagen II and then value of cytotoxicity on hFLSs and liver, the arthritis index, immunocyte in paw joint and DNL, rheumatoid factor (IgG and IgM), collagen II specific antibody in the serum were measured. The cytotoxicity were not shown on hFLSs and liver. The arthritis index decreased significantly after 3 week. In total cell counts of DLN and paw joint, there was a significant increase in DLN and significant decrease in paw joint. In DNL, $CD19^+$, $CD3^+$, $CD4^+$, $CD3^+/CD69^+$, $CD8^+$, $CD4^+/CD25^+$, $ CD3^+/CD49b^+$ cells increased significantly. In Paw joints, $CD3^+$, $ CD4^+$, $CD4^+/CD25^+$ cells decreased significantly. The level of serum IgG and IgM decreased significantly. The level of collagen II in the serum was decreased significantly. Marginal erosion, necrotic chodrocytes, cartilage and bone degradation were improved in histological section of paw joints. The results present significant immunological effect of GDGT on rats with arthritis induced by collgen II. So we expect that GDGT should be used as a effective drugs for not only rheumatoid arthritis but also another auto-immune disease.