We report a 56-year-old man with pulmonary large cell neuroendocrine carcinoma (LCNEC) incidentally found at the surgery for pulmonary aspergillosis. In 1991, an abnormal chest radiographic shadow was found on a mass screening. A diagnosis of pulmonary aspergillosis was made by bronchoscopic examination. The patient was then followed up without treatment. He had hemoptysis in 2005, and was referred to our hospital. Chest CT scan revealed a cavitary lesion with an air crescent sign and an irregularly shaped nodule in the right apex. Wedge resection of these lesions was performed under video-assisted thoracoscopic surgery. Pathological examination revealed not only aspergilloma, but also an LCNEC 11 x 7 mm in size, which was located close to the aspergilloma. Microscopically, nests of tumor cells were distributed peribronchially. Right upper lobectomy and mediastinal lymph node dissection was performed, and the pathological stage was IIIA (T1N2M0). The patient received four cycles of adjuvant chemotherapy with carboplatin and paclitaxel. No recurrence has been observed since surgery. This is the first report describing co-existence of pulmonary aspergilloma and LCNEC.