A 22-year-old woman complained of abdominal discomfort. Ultrasonography, computed tomography, and an endocrinologic work-up revealed a 7-cm nonfunctional tumor at the left adrenal lesion. A transumbilical laparo-endoscopic single-site adrenalectomy was successfully completed in 166 min. The postoperative period was uneventful. The pathologic examination confirmed the solid pseudopapillary tumor occurred in the retroperitoneum. There are only five previous reports of extrapancreatic solid pseudopapillary tumors. In this case, the tumor was separated from the pancreas and no ectopic pancreas was histologically observed. To the best of our knowledge, this case is the first report of a solid pseudopapillary tumor of the retroperitoneum.