Microscopic polyangiitis (MPA) is systemic small vessel vasculitis that is very rare in childhood. MPA is characterized by pauci-immune necrotizing small vessel vasculitis without clinical or pathological evidence of necrotizing granulomatous inflammation. Approximately 90% of patients have glomerulonephritis that is accompanied by a variety of other organ involvement. A 10-year-old girl visited our clinic with clinical manifestations suggestive Henoch-Sch$ddot{o}$nlein purpura nephritis such as purpuric skin rash, abdominal pain, arthralgia on both knees, massive proteinuria and microscopic hematuria. So initially we suspected Henoch-Sch$ddot{o}$nlein purpura nephritis. However, later her perinuclear-antineutrophil cytoplasmic antibodies(p-ANCA) test was positive, and her renal biopsy was consistent with microscopic polyangiitis. We began steroid therapy, combined with cyclophosphamide, ACE inhibitor. Currently she is a 12-year old, and until now she has been regularly examined in the outpatient. We report a case of microscopic polyangiitis initially suspected with Henoch-Sch$ddot{o}$nlein purpura nephritis.