Population exposure has been used in the risk assessment process for environmental noise. The number of inhabitants is essential data for the evaluation of population exposure. However, such data is not opened to the public to prevent privacy violation. There are several existing methods for the estimation of the number of habitants, but only with limited accuracy. The purpose of this study is to propose a more accurate method for estimating the number of inhabitants using web scraping techniques and numerical maps issued by the Geospatial Information Authority of Japan. The number of inhabitants is estimated from the number of households and the census. The number of households is calculated based on the total number of housing that is extracted from using web scraping techniques. The proposed method is found to present a better accuracy of the number of inhabitants for the detached houses while the estimation for apartment houses should be still improved.