PURPOSE:To provide a module sealing/cooling structure, which does not need encapsulation of special gas, such as He gas, and makes possible a high cooling performance and a high-density packaging without sealing with solder. CONSTITUTION:A module sealing/cooling structure consists of a module board 3, sidewalls 4 and a cap 5, with which LSIs 12 mounted on the substrate are covered, a cooling component (a water cooling jacket 6) which comes into contact to the cap, a clamping jig for pressing the cooling component and a module part and components (8, 9, 10 and 11) related to the jig, a soft sealent 7 for inserting in the joints between the substrate and the sidewalls and between the cap and the sidewalls, heat conduction contactors 13 for conducting heat generated in the LSIs to the cooling component and a heat transfer compound 16.