A 62-year-old male was admitted to a local hospital due to a clouding of consciousness in October 2006. On admission, his renal function was observed to have severely deteriorated, which is thought to cause disturbance of consciousness. Laboratory data showed blood urea nitrogen to be 160 mg/dl and the serum creatinine level was 25 mg/dl and, as a result, continuous hemodiafiltration (CHDF) was started. Although his general condition improved, his renal function did not recover. Therefore, regular hemodialysis was started in December 2006. The cause of renal dysfunction was uncertain, because MPO-ANCA was negative, and a renal biopsy could not be done due to the lack of a clear corticomedullary border in his kidneys. In January 2008, he was diagnosed to have microscopic polyangiitis (MPA) because of hemoptysis, elevated serum CRP levels and a positive finding for MPO-ANCA (408.0 EU). An alveolar hemorrhage was also ascertained in a broncoscopic examination. Steroid pulse therapy and intravenous pulse therapy of cyclophosphamide were thus started. The patient's clinical symptoms thereafter significantly improved and his MPO-ANCA level became normalized. This is a rare case characterized by a late appearance of MPO-ANCA, which occurred after more than one year after the onset of renal failure in MPA.