To provide a simply configured foundation structure suitable to supporting a structure that is supported by the base.

The foundation structure, in replace of conventional foundation structures, includes: a plurality of base-isolating mechanisms; and a plurality of buffers, each of which is provided with a first elastic body for generating vertical compressive force, a second elastic body for generating vertical compressive force, a first member having a first attachment surface on one of an upper portion and a lower portion, a second member that is movably guided relative to the first member in vertical directions and has a second attachment surface on the other of the upper portion and lower portion, and a tension member for generating vertical compressive force. In each buffer, a tension member vertically co-fastens the first member, the first elastic body, the second member, and the second elastic body stacked in this order along the vertical direction so that the buffers and the base-isolating mechanisms which are vertically sequentially connected to support a structure.