Spontaneous hemoperitoneum is an uncommon condition, which may be critical even if treated appropriately. The paraumbilical vein is a portosystemic collateral vein that develops in patients with portal hypertension, and is rarely found to be a source of bleeding. Here we present a case report of spontaneous hemoperitoneum due to rupture of the paraumbilical vein successfully treated with balloon-occluded retrograde transvenous obliteration (B-RTO). A 69-year-old man with cirrhosis due to nonalcoholic steatohepatitis was admitted to our hospital with abdominal distention and pain. Computed tomography revealed hemoperitoneum with a dilated paraumbilical vein, and rupture of the paraumbilical vein was diagnosed to be the cause of anemia. B-RTO was performed via the left femoral vein with upstream embolization using microcoils, and thrombosis of the paraumbilical vein was confirmed after B-RTO. The patient was discharged without complications 20 days after B-RTO and he experienced no further episodes of bleeding during the subsequent 6-month period.