By means of ischemic coagulation of the hepatic artery and portal vein in a microwave coagulation experiment of in vivo swine [correction of bovine] liver, we confirmed approximate doubling of the coagulation diameter compared to the usual coagulation. Based on this fact, for treatment of patients with metastatic liver tumor, we developed an ischemic percutaneous microwave tumor coagulation method using IVR method and applied it in one case, and performed laparotomy microwave tumor coagulation in three cases. We performed the ischemic percutaneous microwave tumor coagulation method on one of the cases. Coagulation was performed for one minute at a dose of 100 W for treatment of metastatic liver tumor of 2 cm in diameter via laparotomy. The postoperative CT showed an extensive coagulation larger than 3 cm. A 2 cm liver tumor was coagulated under balloon ischemia of the hepatic vein and hepatic artery for 13 minutes at a dose of 60 W. The maximum coagulation diameter was 5 cm. Extensive coagulation was possible with percutaneous microwave tumor coagulation through ischemia.