The patient was an 87-year-old man whose initial symptom was general fatigue and inappetence. His laboratory data revealed a rise in C-reactive protein (CRP) and white blood cell count (WBC), and CT scan showed suspicious pneumonia. Antibiotics were given to the patient, but his fever and laboratory data were sustained. Follow up examination revealed a high titer (107 U/ml) of myeloperoxidase specific anti-neutrophil cytoplasmic autoantibody (MPO-ANCA). He was diagnosed with MPO-ANCA associated vasculitis. Steroid pulse therapy was started. The patient's clinical symptoms and laboratory data thereafter significantly improved, but after one week the patient's symptom was aggravated and he died. An autopsy was performed, and necrotizing arteritis of the interlobular arteries were found in the kidneys. We found bacterial infective vegetation attached to the aortic valve. Infected thromboembolus and microabscesses were also found in many organs. We report a case of subacute microscopic polyangiitis associated with bacterial endocarditis.