To obtain a heat insulating structural body capable of improving heat insulating effects, humidity controlling effects and smell absorbing effects, by baking a body to be burned comprising a combustible body of an organic substance and mineral powder of an inorganic substance so as to carbonize the combustible body and packing a prepared noncombustible porous char coal as a heat insulating material into a frame.

The combustible body of an organic substance is a combustible substance of animal and vegetable substances such as a residue to be abandoned after production of a food, chaff, pruned branch, fallen tree, leftover, cellulose fiber, etc., in their original form or formed into fixed particle diameters. Powder and granule of clays are used as the mineral powder of an inorganic substance. These raw materials are mixed in a wet state, formed into a pellet shape of fixed particle diameters and baked. A frame 2 into which a noncombustible porous char coal 1 is packed is in a container shape having a feed opening and an exhaust vent. A set amount of the noncombustible porous char coal 1 having fixed particle diameters is packed from the feed opening to the frame 2 by a packing machine or a hand packing operation. When a given amount of the noncombustible porous char coal 1 is packed, the feed opening and the exhaust vent are completely closed.