The reclaimed tract from the sea is commonly called the Kaisaku in Yamaguti Prefecture. Since the rice culture has been of capital importance in modern agricul- ture, the problems of irrigation wich occupy the major part of agricultural technique deserve greater attention and more serious study in the historical science of agriculture. The writers investigated into the practice resecting the irrigation in the Takadomari-Kaisaku by reffering to the historical data preserved at the Nakaya Family.It was 1669 when the Hagi clan succeeded in making the TakadomariKaisaku. Since that time a great improvement for the rice culture in this reclaimed land had been done as the years went by, and the yield came to amount to 22,134 bushels. So important was the water for the irrigation in the rice field, that the problem of allotment of water led farmers and the village authorities to cause a violent quarrel. Consequently the Hagi Government was compelled to take new measures to definitely settle the allotment of the water for the farmers in order to arrange the matter for evermore. The present stipulation for the irrigation water in the Takadomari-Kaisaku is thus derived from the revolution mentioned above.