We report a case of acquired hemophilia A (AHA) after esophageal resection. The patient was an 80-year-old woman whose preoperative activated partial-thromboplastin time (APTT) was well within the normal range, at 34.9 s. She underwent thoracic esophagectomy and gastric pull-up for superficial esophageal cancer (operative time, 315 min; intraoperative blood loss, 245 ml). Intrathoracic and subcutaneous bleeding occurred spontaneously on postoperative day (POD) 39. The APTT was prolonged, at 140 s, and factor VIII inhibitor was 36 Bethesda U/ml. Treatment with recombinant activated factor VII, prednisolone, and cyclophosphamide resulted in remission within 2 months. This case supports an association between surgery and the triggering of factor VIII inhibitors. The diagnosis of AHA requires clinical acumen and must be considered in any patient with bleeding and a prolonged APTT.