Population aging and income inequality are two prominent phenomena across the world．Is aging one of the most important factors influencing income inequality? This paper presents empirical evidence on the effect of population aging on income inequality，using a panel dataset from 76 countries and regions from 1970 and 2011. The empirical results show that population aging does increase income inequality significantly．Moreover，this impact is mainly from top-aging rather than bottom－aging．Population aging also has a greater impact on income inequality in those countries having higher income levels and higher levels of aging．Impact of population aging on income inequality varies with the stages of economic development．The results are robust when several control variables are added in the model as well as potential endogenous problems and abnormal sample points are considered．

Since inequality differs cross population groups，changing population age structure may
have an effect on overall income inequality．This paper develops an analytical ( statistical) model to describe conditions under which population ageing could aggravate income inequality，and show theoretically and empirically that the conditions are true in China．Thus，it is hypothesized that population ageing aggravates inequality in China．With Gini coefficient as measurement of income inequality，and employing provincial level panel data over 1996 － 2009，this paper confirms that population ageing ( i．e．an increasing aged dependency ratio and a decreasing child dependency ratio) is a positive and significant factor contributing to income inequality．This suggests that inequality studies need to incorporate
population ageing，as it conveys different policy implications as compared to other factors．