Anatomic variations of the pulmonary artery increase the risks for vessel injury and critical mistakes during pulmonary artery resection. A patient who underwent left lower lobectomy for lung cancer with a mediastinal lingular and basal pulmonary artery that had been detected preoperatively by three-dimensional computed tomography is presented. During thoracoscopic surgery, the mediastinal basal pulmonary arteries were found with careful dissection. The pulmonary arteries were divided, and left lower lobectomy was performed safely. This rare variation of the left pulmonary artery is important to detect before lobectomy to ensure safe surgery. In such cases, three-dimensional computed tomography is necessary.