PURPOSE: To provide a semiconductor electronic device which has high cooling efficiency by interposing the edge of a substrate in the tapered section of a cold plate to fasten and fix a cam to the cold plate with a bolt or a nut.

CONSTITUTION: A cold plate 5 provided over a controlling LSI 2 has a refrigerant flow path 8 which has a water supply port 6 and an exhaust port 7 at the both ends. The below surface of the edge adjoining a substrate 4 of a cold plate 5 is shaped in sawtooth. A cam 11 provided with a tilted surface corresponding to each tapered section 13 also has a through-hole 15 passing through up and down. A heat connector is formed by attaching the cam 11 to the cold plate 5 by passing a bolt 12 provided with a screw 12a at the edge through the through-hole 15 of the cam 11 and a through-hole 14 of the tapered section 13 and fixing it with a nut 10.