This paper attempts to study Tokyo's response to the emission of greenhouse gases. The volume of emissions of CO2 from Tokyo is greater than many of the developing nations and accounts about 1% of emissions from all developing nations. Tokyo Metropolitan Government seems to be well aware of the problem and is actively seeking for the ways to reduce emission with the goal of reduction by 6% in 2010 from 1992 level (12% from 1998 and 20% from Business-as-usual 2010). This paper firstly discusses the need for Tokyo to reduce CO2 emissions, discusses the framework of national strategies and then evaluates Tokyo's response. Some of the measures of Tokyo could be the guiding principles for other cities in Japan as well in other countries although measures in one city cannot be copied to other cities as it is. At least, the initiatives of Tokyo can be taken as a "front-runner" approach in which many local governments in Japan might follow Tokyo and ultimately the impacts would be bigger, especially when a new law has already been passed from Japanese Diet requiring local governments to make their strategies for GHG mitigation and to contribute towards Japan’s Kyoto Commitment.