Undifferentiated pleomorphic sarcoma(UPS)of the small intestine is extremely rare and has a poor prognosis. We encountered a case of primary UPS of the ileum without metastatic lesions. The patient was a 44-year-old man who presented with the chief complaint of lower abdominal pain for 9 months. He also presented with anemia, hypoproteinemia, and a lower abdominal tumor about 10 cm in size. Abdominal CT with cystography showed an irregular solid tumor with compression of the cystic bladder. Based on a presumptive diagnosis of the retroperitoneal tumor, he underwent laparotomy. An irregular tumor, 9×8×5 cm in size, was observed in the ileum approximately 60 cm from the terminal ileum. There were no lymph node, peritoneal, or liver metastases. Partial excision of 30 cm of the ileum from 50 cm to 80 cm at the terminal ileum was performed. The final histological diagnosis was primary UPS(storiform pattern with fibroblast-like spindle cells). The patient was not administered adjuvant chemotherapy and was discharged on postoperative day 10. He is currently well without any evidence of recurrence for 2 years after the surgery.