To provide a tank for excrement treatment which can be produced at low costs and without requiring any special technique, which never damages its peripheral environment, and which is simple and excellent in durability.

In the tank (2) for excrement treatment connected to an excrement part through a conduit (5), stones piled up to 1.5 to 2.0 m along the inner side face of a rectangular borehole (3) which has an open top face obtained by excavating the ground surface, a depth of 3 to 4 m, a width of 3 to 4 m and a length of 2 to 3 m are painted to be hard with clearances among them filled with gravel and cement to form an inner wall surface. On the bottom surface of the borehole (3), mixed material (8) of the gravel and sand is spread at a height of 2 to 3 cm. The opening of the borehole (3) is covered with a lid (6) made of concrete or plastic having a gas discharge port (6a). A pipe is inserted and fixed to the gas discharge port (6a).