Nuclear medicine therapy is the treatment method that delivers radiation from inside the lesion where the therapeutic agent has accumulated. This can be performed minimally invasively with high antitumor efficacy against metastatic lesions throughout the body. In 2021, Lu-177 DOTATATE for neuroendocrine tumors and I-131 MIBG for malignant pheochromocytoma were approved by insurance in Japan. In addition to conventional I-131 therapy, novel radionuclides such as Lu-177 and Ra-223 are changing the current status of nuclear medicine therapy. In addition, new therapeutic radionuclides, the alpha-emitting radionuclide At-211 and Ac-225, beta-emitting radionuclides Cu-64 and Cu-67, can be produced at several facilities in Japan. With the advent of new therapeutic agents, the laws governing their treatment are being revised to reflect current conditions. On the clinical side, the combination of nuclear medicine therapy and diagnostic imaging, Radio-theranostics, is being implemented more frequently than ever before. In addition, a therapeutic agent for prostate cancer, Lu-177 PSMA, was approved by the FDA. In the immediate future, this is expected to further increase the clinical use of nuclear medicine agents by Radio-theranostics. [ABSTRACT FROM AUTHOR]