Heat-resistant buffer sheet and thermal pressure treatment method

The provided heat-resistant buffer sheet is disposed between a hot-pressing surface of a hot-pressing device and an object during hot-pressing treatment of the object so as to prevent direct contact between the object and the hot-pressing surface, and the amount of change in compressive strain ([Delta] S250), which is the difference (S250-S25) between the compressive strain (S25) at 25 DEG C and the compressive strain (S250) at 250 DEG C, is-5% or more. Wherein S25 and S250 are respectively the compressive strain ST of the heat-resistant buffer sheet at the evaluation temperatures of 25 DEG C and 250 DEG C, which are evaluated by thermomechanical analysis (TMA). The compressive strain ST is determined by the equation: ST = (t1-t0)/t0 * 100 (%), where t0 is the thickness of the heat-resistant buffer sheet at 25 DEG C, and t1 is the thickness of the sheet at an evaluation temperature T (DEG C) when compressive force is applied in the thickness direction of the heat-resistant buffer sheet by TMA. The heat-resist