As the birthrate declines, the population decreases, and the aging rate increases, but to what extent is this a problem? Although the demographic structure of modern Japan has changed dramatically, the economy and society have responded to these changes in a relatively flexible manner. However, the fiscal structure, in which benefits for the elderly are paid for by the working-age population, will be severely affected by the declining birthrate. We will discuss how the fiscal management should respond to such a situation.