Aortobronchial fistula often requires emergency surgery as it causes rapidly progressing respiratory failure. Some patients present with recurrent hemoptysis episodes. We report the case of a patient who was saved by elective surgery after aortobronchial fistula following aortic pseudoaneurysm rupture into the lung. An 84-year-old man, who had undergone mechanical Bentall replacement of the ascending aorta 20 years ago, complained of persistent fever. Computed tomography indicated a pseudoaneurysm at the distal anastomosis of the ascending aorta, and an urgent surgery was planned. During hospitalization, his aneurysm ruptured, suddenly penetrating the right lung and triggering acute respiratory failure and unconsciousness before the planned urgent operation. Mechanical ventilation was immediately provided; his respiratory status remarkably improved through intensive care and medical therapy. After nutritional status recovery, partial arch replacement was performed as an elective operation without any intervention for the injured lung. He did not exhibit any respiratory or neurological complications postoperatively.