A 62-year-old man was admitted to the hospital because of anal bleeding. Abdominal ultrasonography and computed tomography showed a mass of the right lower abdomen. Gastrointestinal barium studies revealed stenosis of the ileum, and angiography demonstrated a hypervascular mass. With a preoperative diagnosis of tumor of the small intestine a partial resection of the ileum was performed. The excised tumor was 7.0×5.0 in size. Pathologically diffuse proliferation of malignant plasma cells was shown. No M. protein and Bence Jones protein were detected. Bone scan and bone marrow puncture were unremarkable. Therefore we diagnosed the tumor as extramedullary plasmacytoma originated from the ileum. Extramedullary plasmacytoma of the small intestine is extremely rare. We report such a rare case with a review of the literature.