To provide a support structure of a cryogenic liquefied gas storage tank hardly causing worsening of global environment and lowering of construction efficiency in construction.

An inner tank forming a storage part of cryogenic liquefied gas is installed inside an outer tank 3 with a heat insulating layer 2 held in between, and an outer tank bottom plate 6 is installed on a concrete base. A bottom part heat insulating layer 2a is installed on the outer tank bottom plate, and an inner tank bottom plate 7 is placed and supported on the outer tank bottom plate through the bottom part heat insulating layer. To constitute the bottom part heat insulating layer, a plurality of cylindrical bodies 9 of approximately the same length are juxtaposed on the upper face of a perlite concrete heat insulating layer 8, placing cylinder axes along a vertical direction, and heat insulating perlite 10 is filled inside the cylindrical bodies and between the cylindrical bodies to form a perlite heat insulating layer 11 which is stacked on the perlite concrete heat insulating layer 8. A cushioning heat insulating layer 12 formed of lightweight cellular concrete (ALC) is further stacked on the perlite heat insulating layer to constitute the bottom part heat insulating layer.