PURPOSE: To physically and electrostatically protect connector portion by bending edges of upper and lower metal plates of case in L-shape, covering from corner of edge faces to vicinity of the connector portion and connecting earth point of built-in integrated circuit to the metal plate.

CONSTITUTION: Metal plates 3 for reinforcement are attached to upper and lower faces of case 1, their edges are folded to have L-shaped portions 31, and formed so as to cover from corner of edge faces where connector part 11 is provided to vicinity of the connector portion. Lead wire 4 connects earth point 23 of built-in IC 2 and the metal plates 4 attached at the upper and lower faces, and guides discharge of static electricity near the connector part 11 to the folded portion 31 of metal plates 4 to prevent discharge to contact pins 21.