This study investigates the reduction in expenses that was anticipated following the Japan＇s Heisei Municipal Mergers. It examines whether differences appear between merged and non-merged areas. The study analyzes the types of influence of the population size（or population growth rate）and geographical area on expense reduction as well as the mergers＇ effect on Japan＇s financial index. Results show that the population size, geographical areas, and presence of the merger influence expenditures. In addition, in the rate of change of the financial index, what population size, geographical area and presence of the merger had an influence on is confirmed. Particularly, it is so in the annual expenditure item in which the comparative expense reduction effects such as obligatory expense and assembly costs easily occurred. In short, something of effects of the socalled Heisei Municipal Mergers is fairly confirmed.