The expected increase in energy consumption during the coming fifteen years is estimated under the assumptions that the Japan's population will reach to one hundred million in 1965 and that the present standard of life should be maintained. Japan in the future cannot depend on wood and coal as energy resources but only way to supply the increasing energy demand would be in full utilization of hydraulic power, for which the necessity of a long-sighted fuel and power policy of the government is stressed by the author.