This paper attempts to perform empirical analysis of the income distribution by age groups of different economic areas in Kagoshima. The author estimates a joint density function of family income and the age of household head for each area with GMM. And then, we derive income distributions by the age groups from the joint distribution. The result shows that, in almost all areas, householders over 60 years old have less income and are subjected to larger income inequality than the younger ones. This study also shows that the further an area is from an urban region, the larger the income inequality of each age group within the area becomes.