To provide a support structure which can develop a vibration proof- base isolation system to a heavy structure by preventing the occurrence of a large restriction to a supportable flat unit area and weight.

An air spring 1 is composed of an elastic side part 3 and a hollow part 9 enclosed by rigid lower and upper face boards 5, 7, and a supporting mechanism 11 is provided in the inside. A high pressure air is poured into the hollow part 9 during operation, and a space 13 exists between the supporting mechanism 11 and the upper face board 7 during operation. Thus during operation, the air spring 1 supports the load of a structure loaded on the upper face board 7 without depending on the supporting mechanism 11. In addition, at a seating time for execution and inspection, in a case where an air quantity in the hollow part 9 decreases, the upper face board lowers to the upper face of the supporting mechanism 11, and the supporting mechanism 11 therefore supports the load of a structure loaded on the upper face board 7.