PURPOSE: To obtain a foundation structure having excellent characteristics such as good drainage, less slippage, adequate elasticity, etc., by filling the void of a porous core member with sand and fixing the sand to the core member by using a rubbery, elastic polymer.

CONSTITUTION: The foundation structure in this invention is provided with a porous core member, which is made up of a core member having void structure like in the core of a gourd or the one obtained by turning a thick polyester fiber (having a large denier) into a staple fiber. Next, the void of the porous core member is uniformly filled with sand, while a latex consisting of rubbery, elastic polymer is spread over the sand and drided so that the polymer is hardened, thereby fixing the sand to the porous core member. As for the rubbery, elastic polymer, the one selected out of a group consisting of natural rubber, synthetic rubber, or its derivative is used.