​Analyzing the relation between population factors and technological progress is the main purpose of this book. With its declining population, Japan faces the simple but difficult problem of whether sustained economic growth can be maintained. Although there are many studies to investigate future economic growth from the point of view of labor force transition and the decreasing saving rate, technological progress is the most important factor to be considered in the future path of the Japanese economy. Technological progress is the result of innovations or improvements in the quality of human and physical capital. The increase in technological progress, which is measured as total factor productivity (TFP), is realized both by improvements in productivity in the short term and by economic developments in the long term. The author investigates the relationship of population factors and productivity, focusing on productivity improvement in the short term. Many discussions have long been held about the relation between population and technological progress. From the old Malthusian model to the modern endogenous economic growth models, various theories are developed in the context of growth theory. In this book, these discussions are summarized briefly, with an analysis of the quantitative relation between population and technological progress using country-based panel data in recent periods.