To improve heat-insulation management and habitability and effectively use the ground, by using temporary construction materials for an earth retaining wall as an external form for a waterproof substrate and reinforcement concrete used in common, to prevent a basement body from moisture and mold by the waterproof protection.

A newel post 1-1 is driven in the ground and a sheet pile 1-2 is closely arranged between a building body and the post 1-1 to form a substrate form of a waterproof layer for a wall and also an external side form used in common. When water has sprung from the ground, a water passage or the like to drain the water to the outside is arranged to remove it and when cutting-off it, leveling concrete 2 is placed on the bottom to form a water proof substrate layer of the floor. A waterproof sheet 3-1 is stuck to the form to form an integral waterproof layer of the floor and the wall and then a foaming resin 3-2 is sprayed thereon. Subsequently, concrete 4-2 is placed on the floor to solidify the bottom bed, and the reinforcements 4-1 of the upper part of the wall and the ceiling are integrally formed and concrete 4-2 of the inside form 5 is integrally placed. And further, after curing of the building body, the foam layer 3-2 and the sheet 3-1 are stuck to the rest external waterproof ceiling and wall. In this way, the waterproof work of basement is finished.