PURPOSE: To prevent the substantial opening of an opening section for inserting a signal conductor when the opening section is not used, and to inhibit the area of the opening minimally when the signal condoctor is inserted by arraying good conductor small-gage wires in parallel at intervals of several mm or less, larger than the diameter of the small-gage wire, and short-circuiting one side ends of each small-gage wire with sheet-shaped good conductors.

CONSTITUTION: Small-gage wires 1 composed of a good conductor are arranged in a row in the same plane, and one end sections thereof are short-circuited by sheet-shaped conductors 2. A metallic wire having large conductivity δ, a material in which a fibrous resin is coated with a metal, carbon fiber, etc., are used as the good conductor small-gage wire 1. The good conductor small-gage wire 1, size of which extends over a range of several dozen μm or several mm practically, is employed, and the size of the small-gage wire<P<several mm holds in the relationship of wire intervals P at a time when the small-gage wires are arrayed and the size of the small-gage wire. The sheet-shaped conductors 2 are mounted inside a box body 3, and the smallgage wires 1, 1 are faced oppositely from the upper side and the lower side at the center of an opening section 4, and stacked. Accordingly, the opening section 4 is shielded substantially with the good conductors by the small-gage wires when signal conductor is connected to a connector 5, and an area opened at a time when the signal conductor 6 is inserted can be minimized.