PURPOSE: To effectively obtain a force against horizontal force by forming a wall connecting foundation piles at a given depth from the ground's surface before or after the construction of the foundation piles.

CONSTITUTION: Plural foundation piles A are constructed by a conventional method, and a connecting wall B is constructed between the foundation piles A by a conventional method to integrally combine both the piles and the wall. After the construction of the connecting wall B, the foundation piles A may be constructed and connected with each other. Thus, a force against a great horizontal force, e.g, earthquake, etc., can be obtained economically and reasonably.