To prevent the metal rupture face of the tip portion of a grip portion formed on a clamp sandwiching and pressure contacting a frame and an inner shield prevent from damaging and separating a blackened film formed on the inner shield.

The intermediate portion of a belt-like elastic metal body of an inner shield coupling clamp 1 is bent into V-shaped so as to form an intermediate bent portion 2 at the top thereof. First bent portion 3 to fourth bent portion 7 are formed by bending successively inward and outward on respective sides extending on both sides of the intermediate bent portion 2, and the superimposed frame and inner shield are sandwiched and pressure contacted by a grip portion 8 and the fourth bent portion 7.