A 46-year-old man had been given 40mg prednisolone daily for systemic lupus erythematosus. He complained of fever and general fatigue and chest computed tomography revealed wide-spread consolidation with multiple cavity formation in his left lung. Pulmonary nocardiosis was clinically suspected because we detected nocardia from Gram staining of sputum. He was cured by sulfamethoxazole-trimethoprim, Imipenem/Cilastatin, although a cavity with a slightly thickened wall in the left lung remained. Nocardia asteroides was cultured from sputum and pulmonary nocardiosis was diagnosed. The present case was pulmonary nocardiosis that spread with multiple and extensive cavity formation. A good outcome was obtained by early treatment with sulfamethoxazole-trimethoprim.