Acute respiratory distress syndrome after pulmonary resection for lung cancer frequently has a lethal outcome. Treatment with a combination therapy of neutrophil elastase inhibitor and steroid administration was used to achieve good control, without impairing lung function, in a patient with postoperative acute respiratory distress syndrome. A 74-year-old man was diagnosed with lung cancer and referred to the outpatient department of Chiba University Hospital with double primary lung cancers located in the right upper lobe that were staged at T2N0M0 (stage IB). He underwent right upper lobectomy with hilar and mediastinal lymph node dissection. After 10 postoperative days, he had acute respiratory distress syndrome. He was given a corticosteroid and a neutrophil elastase inhibitor, which resulted in rapid improvement without lung dysfunction.