PURPOSE: To enable reuse of two works by welding or adhering or cutting off a joint, by a method wherein another substance is provided on two works under a state where the other substance is close to the works by separating from the works and an idle space is provided at the joint of the works.

CONSTITUTION: A substance 1 is provided separately in an adjacent state onto two works 2 to be joined. Then a part of the substance 1 corresponding to a joint of the works is provided with an idle space 3. In the case where welding is performed, the surfaces 4 can be welded together so that the substance 1 will not be fused. In the case where adhesion is performed, the surfaces 4 can be stuck to each other so that the substance 1 is not stuck to the work 2 due to the idle space 3. The surfaces 4 can be cut off so that cutting force will not be applied to the substance 1 due to the idle space 3 further. In the case where the work 2 is cut off like this, it does not happen that the substance 1, which is a nonprocessed substance, is not damaged, and the work 2 can be reduced. Further welding or adhesion or cutting off of the whole of the joint or whole of a section of only the works 2 can be repeated.