A heat-resistant clay membrane and exfoliated graphite - a conventional material of gaskets - are combined to develop a new gasket that is superior to existing nonasbestos products in terms of heat resistance, durability, and chemical resistance in addition to offering the same ease in handling as asbestos products. This gasket offers a wide range of applications in facilities such as chemical plants like oil refineries and heat power plants, taking advantage of its ease in handling and thermostability. Excellent results have already been obtained from the verification tests conducted in petrochemical plants.