To positively prevent a wire cable and a heat insulating material formed out of synthetic resin from coming into contact with each other, by forming a cable protecting member into a cup shape having a bottom wall, a main wall, and a front surface opening.

This cable protecting member A formed into a cup shape having a bottom wall 8, a main wall 9, and a front-surface opening 10, and formed out of polyethylene or the like is inserted into a storing hole 6 so that the bottom wall 8 may cover the lower part of the storing hole 6 and the main wall 9 may cover the periphery of the storing hole 6, thereby providing a coating film, for example, when a heat insulating material is formed out of styrofoam polyethylene and the coating film of an wire cable 7 is formed out of vinyl chloride. A storing hole is drilled from a surface material to the styrofoam polyethylene heat insulating material, wiring accessories 5 are disposed, and an inserting hole is formed in a structural material 4. Thus it is possible to prevent heat insulation from being reduced, and positively prevent the wire cable 7 from coming into contact with the lower and peripheral parts of the storing hole 6.