Study to Evaluate the Efficacy of Tacrolimus in Rheumatoid Arthritis Patients Shown Unsuccessful Response to Methotrexate

Inclusion Criteria: * Patients with more than 6 months history of rheumatoid arthritis according to ACR criteria * Patients who have been treated unsuccessfully to more than single DMARDs including methotrexate at the discretion of investigator * ESR ≥ 30 mm/h or CRP ≥ 1.0 mg/dL (ESR: Erythrocyte Sedimentation Rate, CRP: C-Reactive Protein) * Patients are required to have at least 3 of 66 joints assessed as swollen * Patients are required to have at least 6 of 68 joints assessed as painful with pressure Exclusion Criteria: * Pregnant or breast-feeding patients. Patients who plan to bear children or breast-feed during the study and within 6 month after completion of study * Previous experience of tacrolimus (ointment excluded) * Renal impairment or serum creatinine \> 1.4 mg/dL * Liver function failure as follows: viral hepatitis, non-viral hepatitis, cirrhosis, SGOT/SGPT \> 2x upper limit normal * Patients with history of pancreatitis, glucose intolerance or complication or who indicates any of the following criteria:Blood glucose level \>110mg/dl before the meal and \>200mg/dl after the meal HbA1c \> 6.4% * Cardiac disease(ischemic heart disease, treatment-requiring arrhythmia, heart failure)or complications * Other investigational drug within last 30 days * Patients who have been treated with infliximab, adalimumab, or leflunomide within 8 weeks of start of the study