A 46-year-old man was admitted to the hospital because of abdominal pain and vomiting. The abdomen was distended. There were tenderness, rebound tenderness, and muscle guarding in the right lower quadrant of the abdomen. Simple abdominal x-ray film revealed prominent gas and niveau formation of the small intestine. Intestinal obstruction and peritonitis due to acute appendicitis were suspected, and an emergency operation was performed. During surgery, a moderate amount of yellow transparent ascites was present in the abdominal cavity, but only mild inflammatory findings were seen in the appendix. An exploration of the abdominal cavity revealed an induration in the ileum about 130cm to the ileum end. An oral portion of the ileum from the induration dilated and the narrowed intestinal lumen at the site might cause intestinal obstruction. A partial resection of the ileum including the induration was performed. After the operation when the resected material was opened, redness and thickening of the mucosa were seen. Pathologically transmural infiltration of inflammatory cells mainly composed of eosinophilic leukocytes at the induration was confirmed. Eosinophilic enteritis was diagnosed.