Abstract
In Japan, we have a severe problem, which is the Birth rate of 1.39 is very low, ant it is considered to be still getting low. There are many bad opinions, for example, "The reduction of population will bring the aging problem" or "From now, Japan will be getting weak". In this paper, we analysis reasons of the reduction of birth rate based on the statistical data and our numerical formula. Then we discuss on the means to stop the reduction of population.
