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．