Primary small bowel cancer is a relatively rare malignancy as compared with other malignancies of the gastrointestinal tract. It is difficult to diagnose small bowel cancer because small bowel enteroscopy or wireless capsule video enteroscopy are not applied routinely in most hospital. An emergency operation is generally performed in many cases because of acute abdomen. We experienced a case that we were able to diagnose as small bowel cancer before the operation. The case was a 76-years-old woman. She had anemia and intermittent stomachache. She was diagnosed with small bowel cancer by small bowel enema. In surgical findings, the circular tumor was on the anal side, 90 cm from Treiz's ligament. Partial resection of the small bowel was performed. The pathological fidings was adenocarcinoma of small intestine. The postoperative course was uneventful, and she was discharged on postoperative day 13.