A 44-year-old man, who had suffered repeated episodes of pneumonia since 1984, was admitted with complaints of cough, low grade fever and sputum. Chest X-ray showed a mass shadow in the left lower lobe. Bronchofiberscopy revealed a tumor with a smooth surface which obstructed the B9 bronchus. Left lower lobectomy was performed despite the lack of evidence of malignancy because of the recurrent pneumonia. The resected specimen contained a smooth-surfaced tumor, 18 mm in size, protruding into a bronchial lumen. The pathological diagnosis was leiomyoma of the lower bronchus and the specimen showed organized pneumonia with necrosis in the left S8-S10 region. Primary benign tumors of the lung are rare and leiomyoma of the lung is particularly rare. Only 65 cases have been reported in the Japanese literature. We report here a case of leiomyoma of the lower bronchus.