To secure the safety of a building by constantly maintaining the degree of verticality (horizontality) of the building, without making the building inclined based on uneven settlement, even on the occurrence of the settlement of the building constructed on soft ground.

A foundation 5, which has a shape of an outer periphery depending on a projected area of a building body 10, is laid on the lower portion of the building body 10. An undersurface of the foundation 5 is protruded into the ground E in such a manner as to have an arc shape; a surface coming into contact with the ground E serves as a sliding surface; and the building body 10 is constructed on the foundation 5 in a state in which the center G2 of gravity of the building body 10 corresponds onto the center G1 of gravity as an oscillating base point of the foundation 5.