A 62-year-old previously healthy male who was a welder/smoker/drinker was admitted to Kani Tono Hospital for severe hypoxemia (Day 0). Initial physical and radiological examinations suggested an acute exacerbation of chronic obstructive pulmonary disease. However, respiratory failure developed rapidly, and he died on Day + 4. Aspergillus fumigatus was identified after his death, and he was diagnosed with invasive pulmonary aspergillosis. The clinical and pathological features are precisely described with pathogenetic considerations.