Japan’s energy policy transformation after World War II has been carried out in the logical framework which is called “Changing and Responding”. The energy constraint problems that Japan is facing are manifested as energy supply crisis in the period of economic recovery，oil demand surge in the high-speed economic growth process，oil crisis，“3E” relationship problems，the international oil price fluctuation problem and nuclear safety issues at different stages. To solve these problems，Japan separately established different kinds of energy policy with different orientation in each corresponding historical stage，which are coal based production policy，oil based comprehensive energy policy，crisis resolution based energy management policy，“3E” coordination based multi-target energy policy，“new national energy security strategy” to respond to turbulent international energy market，and continuation of “nuclear power advocacy” policy.