Study of MRA for Polyarticular Juvenile Idiopathic Arthritis (pJIA)

Inclusion criteria * Patients who are diagnosed with rheumatoid factor (RF) positive or negative polyarthritic or oligoarthritic JIA according to the ILAR standards (1997) * Patients aged at least 2 years old and less than 20. * Patients aged less than 16 years old at time of onset Exclusion criteria * Patients with Class IV Steinbrocker functional disorder at evaluation within 2 weeks before initiation of treatment with the investigational product * Patients who have been treated for the underlying disease with a biological agent, such as infliximab or etanercept, within 12 weeks before initiation of treatment with the investigational product