PROBLEM TO BE SOLVED: To set a joined member or a joined part separable so as to reuse them as much as possible by a method wherein an intermediate material formed of material which is turned fragile by hydrogen is interposed between members which are joined together, and the members are joined together interposing the intermediate material between them.
SOLUTION: An intermediate material 1 formed of material which gets fragile by hydrogen is interposed between two members 2 and 3, and the members 2 and 3 are bonded together through the intermediary of the intermediate material 1. Therefore, when the members 2 and 3 are separated from each other, the joined members 2 and 3 are put in a hydrogen environment, whereby the members 2 and 3 can be easily separated from each other without applying a heat or a force or using solvent which is usually used when the members 2 and 3 are bonded together with organic adhesive agent. Material which gets fragile by hydrogen is liable to expand into powder or make exholiation reacting on hydrogen, and concretely, hydrogen absorption alloy can be used as the above material. By this setup, a joined material or a joined part can be reused as much as possible, and we are capable of getting rid of troubles for scrapping or disposing of composite materials or mounting boards composed of these joined parts at a low cost.