PURPOSE: To prevent the uneven adhesion of and infiltration to a resin layer by mixing two kinds of inorganic fiber of different properties in the separated fiber state to form mat shape, then laminating mold releasing paper with an adhesive layer on one side face, and applying specified treatment.

CONSTITUTION: At least two kinds of different property fiber such as inorganic fiber and glass fiber are appropriately selected according to the purpose as joint material, and these are mixed in the separated fiber state and made into a mat shape. As the combination of inorganic fiber, rock wool or ceramic fiber is used as the base, and glass wool or carbon fiber is separated and mixed therein to form nonwoven fabric by various methods. Needling is applied to the obtained nonwoven cloth in the state of the adhesive layer side of mold releasing paper being laminated on at least one side face thereof. The mold releasing paper, adhesive layer and nonwoven cloth are thereby integrated firmly so as not to generate separation.