We report on a 56-year-old male laborer who injured his thorax in a construction field and complained of chest pain. About 3 weeks later, he was diagnosed as multiple rib fractures and hemothorax and found dead 3 days later at his house. At autopsy, the pneumothorax test was positive, due to not pulmonary parenchymal rupture but pleural adhesion and cavitary abscess from Acinetobacter baumannii pneumonia. Acinetobacter baumannii often causes hospital-acquired pneumonia, but rarely causes community-acquired pneumonia. This is the first report in Korea of a positive pneumothorax test at autopsy caused by community-acquired pneumonia due to Acinetobacter baumannii.