This article looks back at the statistical problems on the relationship between the demographic and economic expansion of Japan. The data relating to the number of population cannot be used as it stands for measuring the population increase in Japan since the last century. During the eighteenth and the first half of the nineteenth centuries, neither the demographic, nor the political and economic expansion beyond national frontiers, were part of Japan's national program. There is no evidence pointing to a definite upward trend in population during that period. Population was kept down by rudimentary, but efficient and peaceful, checks. There are strong reasons, however, to believe that it was appreciably higher than suggested by official records. We know little of the trend of population in the decades preceding the Meiji restoration in 1868, but it follows that the increase in the nineteenth century was possibly less than commonly accepted hiherto. All the evidence points to a remarkable, but neither unique or inexplicable, increase of population since the Meiji restoration. The improvements made gradually in statistical recording, call, however, for extreme caution when endeavoring to measure and to explain this increase, at least as regards the earlier Meiji period.