Paraganglioma is a rare neuroendocrine tumor which arises from extra adrenal paraganglionic cells of the autonomic nervous system. We report a case of a giant retroperitoneal paraganglioma. A 43-year-old man referred to our hospital for further examination of a retroperitoneal mass. The patient had neither familial nor past medical history. The blood and urine test, laboratory examinations including cathecolamines, were unremarkable. Abdominal computed tomography showed an enhancing solid mass 13 cm in diameter on the left kidney. The invasion to the left kidney was suspected. Angiography showed the left renal, splenic, middle suprarenal and left inferior diaphragmatic artery feeding the tumor. The splenic and left inferior diaphragmatic artery were embolized before surgical treatment. The tumor, left kidney, adrenal gland and spleen were surgically resected. Histological examination revealed extra-adrenal paraganglioma, and there was no invasion of the tumor to the left kidney, adrenal gland and spleen. The patient has now survived more than 10 months following the surgery without tumor recurrence.