PURPOSE: To provide a frame body structure in form of a pottery or a mold made of heat insulation synthetic resin.

CONSTITUTION: A frame body consists of a side plate 1 whose cross section has a wave shape with a prescribed thickness and prescribed area, a side part connecting leg 5 for linearly connecting both side plates 1 to each other on the bottom end of the side plate 1, a corner part connecting leg 9 for connecting both side plates 1 to each other on the corner part bottom end, a bottom plate 13 which is laid inside a frame formed by the side plates 1, in which penetrating holes 14 are provided vertically at prescribed positions and whose edges inscribed on the side plate 1 are formed in arc edges 15, and a supporting seat 16 in which a projection 17 fit in the through hole 14 of the bottom plate 13 is erected, for supporting the bottom surface of the bottom plate 13. The side plate 1 includes its configuration such as an inner surface vertical wall and a wall having its seat plate horizontally laid in a center part.