PURPOSE: To obtain heat insulating board, which is free from void and strongly withstanding compression, by a method wherein stirred synthetic resin liquid is poured and sprayed from a plurality of holes or slits, which are provided on the face having the length corresponding to the effective width of lower metal hoop member and being parallel and opposite to lower conveyor face, of the pouring distributing pipe of the stirred synthetic resin liquid directly connected to a stirrer.

CONSTITUTION: The lower metal hoop member 1 is symmetrical to centerline having deep inside pockets. A distributing pipe 4 of stirred synthetic resin liquid directly connected to a synthetic resin liquid stirrer 3 is positioned parallel to lower conveyor 8. The stirred synthetic resin liquid 6 is uniformly poured and distributed on the lower metal hoop member 1 from a plurality of pouring holes 5 of stirred synthetic resin liquid cut at position normal to the conveyor below the distributing pipe 4. When voids develop in the stirred synthetic resin liquid 6 between the lower metal hoop member 1 and upper metal hoop member 2, which is urged on the lower metal hoop member 1, the distributing pipe 4 of the stirred synthetic resin liquid is traversed horizontally. Further, when the thickness of the lower metal hoop member 1 is uneven or symmetrical to centerline, the pouring holes 5, the size of which changes from large holes 5A to small holes 5B, are cut on the distributing pipe 4 of the synthetic resin stirring liquid.