The Long-Term Projection of the Population of Spain compiled by the INE constitutes a statistical simulation of the demographic size and structure of the population residing in Spain during the forthcoming 40 years, should the current demographic trends and behaviour be maintained. This therefore involves a long-term extension, for the national population total, of the recently-published Short-Term Population Projection. In this way, these results basically show the long-term effect of the recently observed evolution of birthrate, mortality and migration. Moreover, the simulation was compiled based on a constant annual flow of foreign immigration from abroad of 400,000 persons since 2019.