A 46-year-old man was admitted to the hospital for evaluation of a dense infiltrative shadow in the right middle lung field. Bronchoscopic examination revealed a polypoid lesion in the right middle-lobe bronchus (Bb11(5)). Examination of a biopsy specimen showed a lump with many Nocardia asteroides bacteria. The response to chemotherapy, which included sulfomethoxazole, was poor, and therefore a right middle lobectomy was done. Three mycetomas were found inside the ectatic bronchi in the S5 area. Pulmonary Nocardia mycetoma is rare.