A 95-year-old man with chronic obstructive pulmonary disease and chronic hepatitis C virus infection was treated for acute lung injury caused by Chlamydophila pneumoniae with antibiotics and high-dose corticosteroids. In total, 7,500 mg methylprednisolone and 680 mg prednisolone were administered over 21 days. However, respiratory failure progressed, and chest computed tomography (CT) scan showed bilateral ground-glass opacity and cavity-forming consolidation in the right upper lobe. Despite intensive therapy, the patient died of multiple organ failure on day 7. CT-guided necropsy was performed, and pathological examination revealed invasive pulmonary aspergillosis and Pneumocystis jirovecii pneumonia. Invasive pulmonary aspergillosis and P. jirovecii pneumonia are both life-threatening opportunistic fungal infections. Co-infection of these organisms is rare but possible if the patient is in an extremely immunocompromised state. Short-term but high-dose systemic corticosteroid therapy was considered to be the risk factor in this case. We should pay more attention to immunocompromised hosts who might be suffering from co-infection of opportunistic infections. Moreover, we need to consider preventive measures in such high-risk cases.