<p>A filmy synthetic resin (4) is laminated by extrusion laminating to one side of a sheet-form air-permeable fibrous material (2) having an air permeation rate as measured by the Frazier method, which is the amount of air passing through an area of 1 cm<2> per second, of 0.5 ml/cm<2>.sec or higher. The air-permeable fibrous material (2) to which the synthetic resin (4) has been laminated is heated from the synthetic resin (4) side and sucked from the air-permeable fibrous material (2) side. Thus, the thermally melted synthetic resin (4) is infiltrated into the air-permeable fibrous material (2) to thereby form a synthetic resin layer (3). The synthetic resin (4) is infiltrated to a depth which is at least 15% of the thickness of the air-permeable fibrous material (2). The peel strength between the air-permeable fibrous material (2) and the synthetic resin layer (3) is 1 N/15 mm.</p>
