In Japan, birth rates are declining year by year. If this goes on, half of municipalities will disappear. Recently, there have been many studies on fertility using TFR as a benchmark for municipal unit data. However, when considering the municipal level, it is not sufficient to focus only on the TFR in investigating the reason for the declining birthrate. In this paper, we conducted an analysis of fertility decline by focusing on TFR and women moving in and moving out of regions. We used OLS regression that do not take into account regional differences and Geographically Weighted Regression (GWR) which allows to include regional differences. We could infer that low income and women’s social advancement, which are generally considered to be factors in declining fertility, do not have much of an impact from the results. We also found that there are regional disparities in TFR that cannot be explained by the variables incorporated in this study, and regional disparities were a trend of west high and east low. In addition, when we looked at the policies of regions that have been successful in maintaining their populations, we also found that there are common steps in policies that are successful in maintaining population.