A 62-year-old man with chronic hepatitis was admitted to the hospital because of severe asthma, fever, and a chest radiograph abnormality. He had previously been treated unsuccessfully with several antibiotics in another hospital. The chest radiographs and CT films showed multiple infiltrations along the bronchi and in the peripheral regions of both lungs. Aspergillus fumigatus was detected in a sputum culture and the non-specific serum IgE was elevated. Allergic broncho-pulmonary aspergillosis (ABPA) was suspected and then steroids were administered. Although the asthma symptoms improved after the steroid therapy, lung infiltration deteriorated rapidly, affecting both lungs, and cavitations appeared. We concluded that invasive aspergillosis had developed from ABPA. Itraconazole and amphotericin B were administered, resulting in gradual improvements in the bilateral infiltration seen in the chest radiographs. The patient underwent open lung biopsy to rule out systemic vasculitis. The histological diagnosis was organizing pneumonia without vasculitis and without aspergillus or other organisms. The pathological findings resulted from the intensive anti-fungal therapy. There is a possibility that the temporal steroid therapy may have affected the conversion of ABPA to invasive aspergillosis.