A 64-year-old man diagnosed as lung adenocarcinoma with hepatic tumor was admitted to our hospital. He carried the hepatitis B virus but was negative for PIVKA-II and alpha-fetoprotein, and hence we diagnosed a case of stage IV lung adenocarcinoma. We planned to administer systemic chemotherapy, but he experienced sudden-onset abdominal discomfort accompanied with decreased blood pressure. We diagnosed hemorrhagic ascites due to spontaneous rupture of the liver tumor. Emergency angiography and therapeutic embolization stabilized his clinical condition. Hemorrhagic ascites due to metastatic liver tumor is rare and the sudden onset of abdominal symptoms is an indicator of rupture.