A 64-y-old male with steroid-induced diabetes mellitus was admitted to our hospital because of a nodular shadow found by chest radiography. Pathological examination revealed pulmonary cryptococcosis, and he was positive for serum Cryptococcus antigen. After oral treatment with fluconazole, he experienced clinical and radiographic improvement, but during ensuing observation without antifungal treatment his respiratory symptoms gradually worsened. Chest radiography showed progressive infiltration around the cavity, and Aspergillus mold was isolated by transbronchial lung biopsy from the lesion where previous cryptococcal infection was present. In addition, serum antibodies to Aspergillus antigens were demonstrated by immunodiffusion. Thus, pulmonary aspergillosis was found to complicate a case of pulmonary cryptococcal infection.