A left lower lobectomy was successfully performed in a lung cancer patient with anatomical variation in which the left superior and inferior pulmonary veins were connected to the left atrium after forming an extrapericardial single trunk. This variation is surgically important because ligation and division of the left inferior pulmonary vein may result in blockage of upper lobe vein drainage at the time of a left lower lobectomy. The ligation of the pulmonary vein leads to severe lung edema, which may cause infection, respiratory distress, or postoperative complications that could be life-threatening. Surgeons must always pay attention to this variation when performing a left lower lobectomy.