PURPOSE: To control the movement of water in the ground, and what is more, to control the water permeability of the earth layer arbitrarily by installing an opening which exceeds the rising level of capillary water with a specific area ratio in a part of non-permeability film buries in the ground.

CONSTITUTION: A non-permeability film 1 and a hole 2, which bores an opening on a part of the non-permeability film 1 and rough particles, such as gravel are set up on the surface of earth 7. The earth 7 is covered with earth 8 up to a required height. An opening 2 is installed to an elevation which exceeds a rising level of capillary water whose area ratio is as large as 1/108 to 1/2. This construction makes it possible to enhance the water retentivity of an upper part earth layer of a buried film 1 with a minimum material and labor and prevent the water in the lower part earth layer from moving to the upper part earth layer and hence control the permeability.