A heating pressure processing apparatus in which gas sealing property and safety can be ensured, and economic property can be improved in heating pressure processing of workpieces such as Si wafers sheet by sheet. A processing vessel 1 formed of vessel components 2, 3 is divided into at least two parts or more in the axial direction thereof and has a seal ring 9 provided in the divided parts of the vessel components 2, parts 3 in such a manner as to be replaceable. The vessel components 2, 3 have shaped parts forming a processing space 5 for a workpiece 4 when the divided parts are sealed through the seal ring 9, the vessel components 2, 3 also having cooling means 10 for the seal ring 9. A ram is provided 18 for pressing the vessel components 2, 3 in the axial direction of the vessel in order to ensure the sealing in the divided parts; and a gas introducing device 20 is provided for introducing a pressurized gas to the processing space 5 in order to process the workpiece.