A 45-year-old man was admitted to our hospital with high fever and a large amount of gray sputum. His initial chest X-ray showed broncho-bronchiolitis and thickening of the large bronchus, and he was subsequently diagnosed with pulmonary aspergillosis based on his sputum culture, polymerase chain reaction for Aspergillus fumigatus, and mannan antigen for Aspergillus. His immune responses, including neutrophil phagocytosis function and neutrophil sterilizing function, were normal as far as we could determine. He was treated with itraconazole, amphotericin B, and meropenem trihydrate, but died of respiratory failure on the twenty-fifth hospital day. Chest X-ray showed rapidly progressive invasive shadows in both lung fields, resulting in multiple cavity formation. This was a rare case of invasive pulmonary aspergillosis in a diabetic man with normal neutrophil phagocytosis function and neutrophil sterilizing function.