A 54-year-old man was admitted at our hospital with a complaint of sudden anterior chest pain. At 1 year previously he had undergone right transthoracic esophagectomy for cancer followed by reconstruction using a gastric tube through a posterior mediastinal route. Upper gastrointestinal endoscopy confirmed a gastropericardial fistula. He was therefore given emergency intensive proton pump inhibitor together with gastric tube decompression using a nasogastric tube. Transabdominal pericardial drainage was surgically performed through a retrosternal space at 4 days after the onset. On the 22nd day after the drainage operation, upper gastrointestinal endoscopy showed healing of the gastropericardial fistula, and he was discharged on the 38th postoperative day. A gastropericardial fistula in the gastric tube following esophagectomy for cancer could be treated with less-invasive procedures including surgical pericardial drainage. Our procedure may be recommended as initial emergency treatment before more invasive procedures such as gastric tube resection and muscle flap plombage.