Abstract: A vacuum heat insulator comprises compressed glass fibers, a planar thin metal plate and a drawn metal plate. A receptacle is air-tightly formed of the planar thin plate and the drawn metal plate. The glass fibers are encased in the receptacle under a vacuum condition. A small amount of the glass fibers is penetrated thereinto in a direction perpendicular to the heat transfer direction of the insulator by inserting needles having hook portions into the glass fibers whereby the compressed glass fibers are kept under a vacuum condition at a high density without any remarkable deformation.