A 44-year-old man was admitted to our hospital with abdominal pain. Enhanced abdominal computed tomography demonstrated intraperitoneal free air and fluid collection. Peritonitis due to intestinal perforation was suspected and an emergency laparotomy was performed. Exploration of the abdominal cavity confirmed perforation of the ileum at a site 20cm from the terminal ileum. Therefore, we performed partial ileal resection that included the perforation and placed an ileostomy. Histopathological examination of the ileum revealed infiltration of eosinophilic leukocytes between the submucosal and subserosal layers, compatible with the diagnosis of eosinophilic gastroenteritis.