PURPOSE: To surely and easily separate the part which eliminates the need for jointing after press-contacting work and to stably manufacture without a personal difference by composing the carbon steel foil to use together with the titanium foil as the stripping material of the steel carbon content volume is higher than the dummy material.

CONSTITUTION: For example, when four sides of the laminating surface of the clad steel blank material assembled by using the dummy material of carbon steel is welded, heated and rolled, and the laminated material of the base steel material and the Cu system metal is press contacted, the forming of the titanium carbide structure layer is advanced faster between the carbon steel foil with higher carbon content than the dummy material and the titanium foil during this treatment. Therefore, the sufficiently weak layer is interposed at the boundary surface of the carbon steel foil with the titanium foil having priority over the boundary surface between the dummy material and the titanium foil, so applying the force to strip the dummy material after cutting the clad material to the prescribed dimension, the titanium carbide weak layer formed at the boundary surface between the carbon steel foil and the titanium foil is easily destroyed, and the dummy material is easily stripped in the state with the titanium foil stuck as it is.