The patient was a 76-year-old man who had 3 times previously undergone laparotomies, including distal gastrectomy with a Billroth Ⅰ operation. In the current case, a total gastrectomy, end-to-side esophagojejunostomy, and a Roux-en-Y anastomosis for adenocarcinoma of the remnant stomach were performed. On postoperative day (POD) 7, he complained of epigastralgia. Abdominal CT revealed a markedly dilated duodenum, and a diagnosis of acute afferent loop obstruction was made. Emergency endoscopy revealed edematous stenosis of the Y-anastomotic site. A nasal endoscope could not pass the stricture, but an endoscopic nasobiliary drainage (ENBD) catheter was successfully inserted into the duodenum. Epigastralgia decreased after drainage. Stenosis of the Y-anastomotic site was still observed 18 days after onset; therefore, we inserted 1 endoscopic retrograde biliary drainage (ERBD) tube, in addition to the ENBD catheter. Twenty-five days after onset, slight improvement of the stenosis was observed. By inserting 2 more ERBD tubes, the ENBD catheter could be removed. On day 28, abdominal CT revealed reduced dilatation of the duodenum. On day 29, oral intake was initiated, and the patient was discharged from the hospital on POD 66. During the early post-operative phase, the use of nasal endoscope drainage is an effective, minimally invasive, and safe procedure for decompression of the duodenum in afferent loop obstruction.