PURPOSE: To easily inspect deformation of a heat insulation cup from the outside without decomposing a heat insulation layer, said heat insulation cup being provided inside the heat insulation layer among a plurality of heat insulation cups in the heat insulation layer including this plurality of heat insulation cups provided multiply in a hot isotactic pressurizing apparatus.

CONSTITUTION: Deformation of a heat insulation cup 41b provided inside an outermost heat insulation cup 41a is inspected by moving and sweeping a proximity switch 7A on an outer peripheral surface of the outermost heat insulation cup 41a of a heat insulation layer 4. Hereby, the residual life of the heat insulation layer can be estimated so that there can be eliminated the possibility that the heat insulation layer reaches the life unexpectedly and time is taken to exchange it and hence a stoppage time interval of a hot isotactic pressurizing apparatus is prolonged, and hence an apparatus operation rate is improved.