This paper analyzes the impact of a population aging on the local public finance in Nagoya city, using a regional econometric model with the data of the cohort-component method. This model is a macro-econometric model of Nagoya City, for this purpose, the budget sector to be carefully estimated by components, on one hand, and the population sector to be built, using the data of the cohort-component method, on the other hand. The analysis is based on a simulation for a prediction period of 1999-2010 using the data estimated by the cohort-component method. From the results of simulation, we find that a primary balance government budget deficit defined by [(government expenditure-public loan)-(government revenue-local public bond)] is increasing in this period and reaches 194 billion Yen in 2010.