Study to Compare the Efficacy and Safety of CELBESTA® and CELEBREX® in Patients With Rheumatoid Arthritis

Inclusion Criteria: * Anyone over the age of 19 * Subjects who are diagnosed as established rheumatoid arthritis at screening visit and before * Pain greater than 40/100mm-VAS(Visual Analgue Scale) after wash-out period * Patients who are taking oral corticosteroids without dosage change (within a range of prednisolone 10mg a day) at least 4weeks and more than 1 DMARDs at least 3 months from screening test * Patients willing and able to provide signed informed consent after the nature of the study has been explained Exclusion Criteria: * History of angina pectoris or congestive heart failure at rest or minimum activity * History of myocardial infarction or artherosclerosis * Patients who had a coronary angioplaty or coronary artery bypass graft within 1 year * History of stroke, transient ischemic attack or hepatitis within 2 years * Patients who have uncontrolled hypertension at screening * Patients who take the medicines that might effect the test results by study investigators or might cause a excessive risk to the patients * Intra-articular corticosteroid injection within 4 weeks from screening * biological DMARDs such as infliximab, adlimumab, entanercept, anakinara or abatacept wihin 6 months from randomization * biological DMARDs such as rituximab within 1 year from randomization * History of a malignant tumor (except for the patients whose tumor was removed and there's no recurrence within 5 years) * Patients who have gastrointestinal bleeding or peptic ulcer (except scar) within 30 days * History of a gastroesophageal surgery such as antigastric-secretion surgery or esophagogastrectomy (except a simple perforator surgery) * Patients who have severe disability in GI, Kidney, Liver and Blood * Pregnant women, Lactating women and Women of child-bering potential who are not using adequate means of contraception * History of allergy to COX-2 inhibitors or sulphonamides or other NSAIDs * Any condition that, in the view of the investigator, would interfere with study participation