To improve productivity by making it possible to easily automate stable and reliable work of blocking a communicated space inside a wire harness, with regard to a material which blocks the communicated space inside the wire harness.

Fusing tapes T1 are wound so that they can be deposited onto each circumference at roughly the same position of electric cables C making up of a wire harness. Then, these are all covered by a heat-shrinkable tube P2. By heating these fusing tapes T1 and heat-shrinkable tube P2, the wire harness is squeezed to a smaller diameter as the heat-shrikable tube P2 shrinks and as its consequence the spaces between the electric cables C are filled with the material of the fused fusing tape T1.