We experienced a successful case in which the patient was treated with a combination of operation and transcatheter arterial chemoembolization for a hypervascular tumor of unknown primary origin in the liver; we report this case with a literature review. A 76-year-old man noticed an upper abdominal tumor and he visited our department for detailed examination. Enhanced CT scan showed multiple hypervascular tumors scattered across both lobes of the liver, and the pattern of contrast effect implied that the tumors were primary neuroendocrine tumors or endocrine metastases. Gastroscopy and colonoscopy showed no tumor in the intestine. TACE was performed mainly for the tumors in the right lobe. One month later, we performed left lateral segmentectomy and partial hepatectomy for segment 6. Histopathological findings showed that the tumors in the left lateral segment had neuroendocrine properties, and the tumor in segment 6 was necrosed. One year has passed since the surgery without recurrence of neuroendocrine tumors in the liver or other organs.