Ageing has been regarded as an important social concern for Taiwan. This paper extends research on the difference in ageing factors between Taipei City and Taiwan's rural area in terms of the changes in fertility, mortality, and mirgration rates. The equations developed by Preston et al. have been adopted to decompose the rate of ageing measured by the mean age. The analysis--based on data collected from 1968-1993 demographic data in Taiwan-Fukien Demographic Fact Book, Republic of China--provides strong evidence that population process (fertility, mortality, and migration) has different influence on their population ageing of Taipei City - and Taiwan's rural area. Being compared with ageing in overall Taiwan area, the suppressive effect of changes in natural factors (including birth and death rates) on ageing of rural area is stronger than that of overall Taiwan area, and it is also larger than that of Taipei city. However, the social factor (migration) shows pulling up ageing in rural area while it presents pushing down ageing in Taipei City.