This study treats the problem about merger and abolition of elementary schools in rural region from the standpoint of management with minimum cost and improvement of education environment with integer programming. As a result, it has become clear that the merger and abolition of elementary schools contribute to reduce the cost even for the rural regions whose density of pupils is as high as 473.1 pupils/km². This finding is applied also for the cases, in which class with 25 pupils would be adopted for the regions whose density of pupils is approximately equal to or lower than 8.2 pupils/km².