A hot isotropic pressure device including: a casing disposed inside a high-pressure container; a heating unit provided inside the casing and forms a hot zone around the treatment material, in which an isotropic pressure treatment is performed on the treatment material using a pressure medium gas. A cooling unit is provided to cool the hot zone by guiding the pressure medium gas, cooled while guided from the upper side toward the lower side at the outside of the casing, into the hot zone. The cooling unit includes a gas introducing unit which guides the pressure medium gas cooled at the outside of the casing from the lower portion of the high-pressure container to the upper portion of the hot zone without any intersection with the pressure medium gas inside the hot zone and introduces the pressure medium gas into the hot zone.