Pulmonary thromboembolism is a fatal perioperative complication in general thoracic surgery. There is a report on its incidence of 2.68 cases out of 10,000 general thoracic surgeries. To prevent pulmonary thromboembolism, risk evaluation of an individual case and steady implementation of recommended preventive techiques are required. Because of the prevalence of guidelines for prevention, the incidence of pulmonary thromboembolism in the perioperative period is reducing. However, maximum prevention of deep vein thrombosis(DVT), which can lead to pulmonary thromboembolism, is impossible even if preventive measures are strictly implemented in the perioperative period. Mindful of potential DVT postoperatively, it is crucial to speculate perioperative acute pulmonary thromboembolism when sudden sensation of postoperative dyspnea occurs. For lifesaving measures, treatment along with diagnosis is necessary. In the presence of shock, pulmonary endarterectomy is recommended with percutaneous cardiopulmonary support, while in the absence of shock, treatment depends on a patient's condition.