A 54-year-old man was treated with an antifungal agent (itraconazole) for post-tuberculous intracavitary aspergillosis. Though clinical and radiological findings indicated that the patient's symptoms had gone into remission, aspergillosis recurred 4 months after the cessation of antifungal chemotherapy, requiring that the patient undergo an operation. Intraoperative and pathological findings revealed a squamous cell carcinoma contiguous to the cavity containing the aspergilloma. Though a few cases of aspergilloma within cavitating pulmonary carcinomas have been reported in the literature, the case of lung cancer we report was thought to arise from preformed lung scars surrounding a post-tuberculous cavity that contained an aspergilloma. Although conclusive distinctions between neoplasms and fungal infections are difficult to make, careful observation of the radiographic features is necessary when treating patients with fungus ball-type aspergillosis.