This paper aims to broadly overview poverty indexes, to investigate their underlying economic theories, and to consider important future study points. We firstly compare the concepts of absolute poverty and relative poverty, and discuss how we should define poverty. Secondly, we summarize the axioms which the representative poverty indexes satisfy and their outstanding characteristics. Thirdly, we examine the main factors of the change in poverty level during the 2000s in Japan, using decomposition methods, and draw policy implications. Fourthly, we introduce the outline of new frontiers for poverty measurement such as the consumption dominance curve and multi-dimensional poverty indicies including the Alkire and Foster method and time poverty. In recent years, much poverty research which crosses into various types of collaborative academic fields such as medicine, epidemiology, and psychology as well as the social sciences have been actively conducted. It can be expected that constructive researches associated with amalgamation of a variety of academic fields will make progress in the future.
