Retractile mesenteritis is a rare inflammatory mesenteric disorder with unknown etiology. We reported a resected case of mass-forming retractile mesenteritis. A 64-year-old man noticed a mass with mild tender in the right lower abdomen. Colonoscopy revealed no abnormal findings. Computed tomography of the abdomen showed a solitary tumor of the ileocecal mesentery. Ileocecal resection was performed. Pathological findings were inflammatory change of the mesentery with marked fibrosis. Final diagnosis was retractile mesenteritis. He is doing well for 26 months after the operation.