A 25-year-old Chinese man visited our institution due to fever and left chest pain. A chest CT showed infiltrative shadows with pleural effusion. Despite antibiotics treatment, his symptoms gradually worsened. The contrast CT showed deterioration of infiltrative shadows with thromboembolism in pulmonary arteries, suggesting pulmonary infarction. Thereafter, his HIV test turned out to be positive. His symptoms and radiological findings improved after initiation of an anticoagulant therapy. No known risk factors for thromboembolism were identified except HIV infection. The possibility of pulmonary thrombosis should be noted when the HIV patient with acute chest pain and pneumonia-like infiltrative shadow is seen.