Unilateral absence of a pulmonary artery (UAPA) is a rare congenital cardiovascular malformation and clinical experience of the surgery for this disease are limiting. We report a case of 62-year-old woman of UAPA (absence of left pulmonary artery) underwent a wedge resection of right lung for metastatic lung cancer. The surgery was performed under double lung ventilation because abnormal lung does not contribute to gas exchange. We were able to perform a wedge resection easily by setting the thoracotomy wound right above the tumor in the spine position. In a performing thoracic surgery under double lung ventilation, the position of surgical wound is very important. Therefore, although the diagnosis of this disease is difficult for the rarity and its nonspecific presentation, preoperative diagnosis of UAPA is very important.