We report a rare case of a extrarenal retroperitoneal angiomyolipoma. A 64-year-old female visited our hospital because of an abdominal mass in her lower right abdomen. Enhanced CT scan revealed a 67×52mm tumor in lower right retroperitoneal space. MRI revealed adipose component in the tumor on T1 weighted images and T2 weighted images. Our preoperative diagnosis was retroperitoneal liposarcoma, and we performed retroperitoneal tumor resection. At operation the tumor was on the fossa iliaca, which was covered with capsule. It did not invade surrounding tissues. The resected tumor measured 90× 60×45 mm, and tiny hemorrhage was seen in the tumor. Histopathological findings showed that the tumor was composed of a mixture of adipose tissue, vessels, and smooth muscle. Immunohistochemistry demonstrated the tumor was stained with asmooth muscle actin(aSMA). We diagnosed the tumor as extrarenal retroperitoneal angiomyolipoma.