Microscopic polyangiitis(MPA) is a systemic necrotizing vasculitis that involves many organ systems including the skin, joint, kidneys, and lungs. In spite of early diagnosis and intensive care, the five-year actuarial patient and kidney survival rates are 65% and 55%. We experienced a case in 7-year-old girl of microscopic polyangiitis presenting with rapidly progressive glomerulonephritis which was confirmed by renal biopsy and positive serum perinuclear antineutrophil cytoplasmic autoantibodies(p-ANCA). The diagnosis of patients first renal biopsy was MPA, p-ANCA-associated crescentic glomerulonephritis. The patients second renal biopsy was done 5 years 6 months later since first renal biopsy, and pathologic diagnosis was chronic sclerosing glomerulonephritis, advanced, due to MPA. We began methylprednisolone pulse therapy, combined with a low dose of cyclophosphamide and plasmapheresis therapy. ACE inhibitor, angiotensin II receptor blocker, and cyclophosphamide were used until now and the patients current age is 14 years old. On admission, the patients laboratory findings showed BUN 117 mg/dL and Cr 2.3 mg/dL, while on the hospital day BUN and Cr values fell to 20.8 mg/dL and 1.6 mg/dL. But renal function was progressed to chronic failure with latest laboratory data BUN 51.7 mg/dL and Cr 3.2 mg/dL. ACE inhibitor, angiotensin II receptor blocker and small dose of immunosuppressant with close observation is the key to maintain the patient survival.