Observing Table 4, it is known that the extent of population aging is almost anti-proportional to the size of municipality. According to the Table, the percentage of total population in the elderly ages of 65 and over as of 1990 recorded 21.8% for the municipalities with less than 5,000 inhabitants and it decreased gradually with the increase of population size of municipality. And, It showed the lowest of 9.3% for the municipalities with the population between 500,000 or more and less than 1 ,000,000, although it indicated a higher percentage (10.5%) for the large cities, or the municipalities with more than 1,000,000 inhabitants.
Also, according to Table 5 presenting the indices of population aging for 13 large cities, the percentage of total population in the elderly ages of 65 and over as of 1995 was the highest (15.8%) for Kitakyushu while it was the lowest (9.4%) for Chiba. Among 13 cities, only Kitakyushu showed higher percentage than the national average. The aged dependency ratio recorded more than 20 for Kitakyushu and Kyoto. However, the elderly-child ratio exceeded 100 for four cities of Tokyo, Kyoto, Osaka and Kitakyushu. Above all, it should be noted that it indicated 114 for Tokyo.
The fact that a little higher extent of population aging is recognized in the large cities having one million or more inhabitants than in the cities with the population of less than one million suggests another aspect of population aging in the large cities, which may be somehow different from the aspect in the smaller cities. Table 6 may give one of the concrete implications for the suggestion described above. According to the Table, presenting the indices of population aging for each zones delineated by radii increasing at every 10km from the metropolitan center, respectively for the metropolises of Tokyo, Osaka and Nagoya, it can be found that the degree of population aging is higher in the central part than in its outer neighboring zones within a metropolitan area.
