We encountered a case of a girl where Human Parvovirus B19 infection was considered to have been concerned with the development of systemic type juvenile rheumatoid arthritis (JRA). While the affected child did not show any evident infectious erythema-like findings, changes in the serum antibody titer by the EIA method presented the pattern of first infection. During the clinical course the condition of the disease as JRA was serious and hemophagocytic syndrome developed concurrently. Furthermore, the resistance to the treatment was also noted. So the patient was treated with prednisolone combined with low dose weekly MTX therapy. The possibility of Human parvovirus B19 being concerned with the development of rheumatoid arthritis in one form or another has been suggested in recent years. In the disease type with systemic angititis as main pathophysiology, which is called systemic JRA we encountered this time, it is not clear how Human Parvovirus B19 was concerned with the development of this disease, but it appeared to hold a key position in studying pathophysiology of the development.