To provide a support structure and a support construction method of a structure capable of exerting high seismic isolation performance and preventing subsidence and inclination of the structure by preventing liquefaction of the ground.

A pressure-resistant wall 2 enclosing the ground G below the structure 1 is provided under the ground G. The region enclosed by the pressure-resistant wall 2 is regarded as a compressed-air zone X, where the air pressure is increased by injection of compressed air while the ground water level is lowered. Permanent ground anchors 6 are embedded in a support layer G2 of the compressed-air zone X, and hydraulic jacks 7 are provided immediately above the permanent ground anchors 6. Strands 8 are extended between the permanent ground anchors 6 and the hydraulic jacks 7. The strands 8 prevent the structure from floating when the air pressure of the compressed-air zone X rises.