PURPOSE: To obtain a resin sealed device which is strong against mechanical shocks, by settling a semicondutor element on a heat sink, and providing a groove wherein the heat sink is exposed to a part of the sealing resin.

CONSTITUTION: The semiconductor element 4 is mounted on the heat sink 2 serving as a common electrode lead by a solder 5 and sealed by the resin 1. Surrounding the element 4, the groove 3 reaching the heat sink 2 from the surface is provided in the resin 1 in a U-form. Mechanical shocks from the outside are absorbed by the groove 3 resulting in the protection of the element 4. The groove 3 can be easily formed when processing by a molding die. By the formation of the groove 3, pre-coat resin is unnecessitated, the cost reduction and the improvement of the strength against thermal fatigue of the solder can be obtained, and accordingly the reliability improves.