Interposition of a jejunal pouch after proximal gastrectomy is a popular reconstruction method in Japan, because it produces a good quality of life soon after surgery. Many reports have described its usefulness. However, there are few reports describing its complications. We report here for the first time a case of pouch stasis needing surgery. A 23-year-old man underwent proximal gastrectomy with interposed jejunal pouch for traumatic strangulated diaphragmatic hernia. Three years later, he complained of persistent vomiting. Since surgery, he had eaten as much as other young people. An upper gastrointestinal series showed dilatation of the jejunal pouch and stasis of contrast medium. Since conservative therapy was not effective, surgery was performed. In the operative findings, the jejunal pouch was extremely dilated, the remaining stomach had become atrophic, and moreover, the anastomosis was severely distorted. It was considered that frequent excessive ingestion caused irreversible dilatation of the jejunal pouch, resulting in pouch stasis. Even though the jejunal pouch is interposed for reconstruction, it is very important to give nutritional guidance to patients, especially young patients, to prevent pouch stasis caused by excessive food ingestion.