PURPOSE: To obtain a superplastic Al alloy having an excellent diffused junction property by preparing a core material of the Al alloy and a skin material of pure Al, and manufacturing a cladding material by specified working conditions.

CONSTITUTION: As for a core material, one kind of alloy selected from each alloy of Al-Cu, Al-Mg, Al-Mg-Si, Al-Zn-Mg, and Al-Li is brought to homogeneous heat treatment. As for a skin material, Al whose purity is ≥99.5wt%, consisting of ≤0.10wt% Si, ≤0.20wt% Fe, and ≤0.15wt% other element is used. A clad material of one face or both faces is formed by hot clad rolling, and thereafter, heating holding of one step or two steps is executed at a temperature of 350W550°C, and said material is cooled by a cooling speed of ≥30°C/Hr. Subsequently, cooling rolling of at least ≥30% is executed, or cold rolling of 20W 60% is executed, and thereafter, low temperature softening annealing of ≤30°C and cold rolling are executed once or more.