Anomalous retro-psoas artery is an extremely rare congenital anomaly of the iliac arteries reported in the English-language literature. Using contrast-enhanced computed tomography, we incidentally diagnosed an anomalous retro-psoas artery in a 60-year-old male patient with right renal cancer. Although anomalous retro-psoas artery is extremely rare and mostly asymptomatic, knowledge of it is needed to avoid severe vascular complications in the event of vascular intervention and surgery.