To Evaluate 1 Year Extension Study of the Efficacy and Safety of Tocilizumab in Patients With Moderate to Severe Rheumatoid Arthritis

Inclusion Criteria: * Patients Who have been satisfied the in/exclusion criteria of CWP-TCZ301 * Patients who have been withdrawn after receiving escape therapy or completed treatment during 24weeks in CWP-TCZ301 study * Patients who able to enroll in this study within 12 weeks after last infusion of CWP-TCZ301 * Willing to give written informed consent Exclusion Criteria: * History of severe allergic or anaphylactic reactions to Investigational product in CWP-TCZ301 study * ALT or AST \> ULNⅹ2.5 * Platelet count \< 100ⅹ103/ μL * WBC \< 3,000/mm3 * Absolute neutrophil count \< 1,000/mm3 * Absolute lymphocyte count \< 500/mm3 * Total bilirubin \> ULNⅹ2