A semiconductor chip 36 is mounted on a package substrate 30 with its circuit side facing to a board 38. Heat is dissipated from an upper side of the semiconductor chip 36 opposite to the circuit side. A sealing resin 32 seals around the periphery of the semiconductor chip 36 so that the upper side of the semiconductor chip 36 is exposed to atmosphere. A fixing member 34 is buried in the sealing resin 32 so that a hook 40 formed on the tip of the fixing member 34 extends above the upper side of the semiconductor chip 36. A spreader 10 dissipates heat emitted from the semiconductor chip 36. A guiding slot 12 is formed on the side facing to the package substrate 30 of the spreader 10. The hooks 40 of the fixing members 34 are inserted into the guiding slots 12 respectively, and then the spreader 10 is rotated by predetermined angle against the package substrate 30. Then, the hooks 40 travel along the slots 12. Through such process, the spreader 10 is pulled to come into contact with the upper side of the semiconductor chip 36.