This paper discusses enactment and enforcing processes of the Japanese renewables Feed in Tariff (FIT) Law and its amendment of 2017. Thanks to the introduction FIT in 2012, the installed capacity of renewable energy is growing rapidly. As of 2015, the renewable electricity ratio in the generated electric power amount of Japan is 14.6 percent. Meanwhile, the levy burden (surcharge) reached JPY 2.1 trillion (aprx. USD18.7 billion). Through the enactment process of the FIT Law, the upper limit of the burden initially determined by the Japanese Diet was removed. A fundamental measure could not be taken to control the installation and the burden since the law does not allow for revisions on the system based on the results of renewable installation, even if the financial burden increases rapidly. Therefore, the Japanese Diet weakened the efficiency of the FIT Law in Japan.