A 70-year-old man had been undergoing image-based clinical observation without treatment for idiopathic pulmonary fibrosis. A bronchial wash was performed because computed tomography imaging revealed a shadow with an air-fluid level during a regular checkup. Fusarium solani was detected in the culture from the bronchial washing fluid, and Fusarium sp. was detected at the reexamination that was performed about one month later. Therefore he was diagnosed with pulmonary fusariosis. Subsequently, he was hospitalized for pyrexia, chest pain, and aggravated pulmonary shadow. The patient was discharged after oral administration of voriconazole resulted in improvement of his condition. We believe that this case provides valuable information because chronic respiratory infection caused by Fusarium is extremely rare, and few reports have described treatment for this condition.