To provide a three-dimensionally formed composite of aluminum, an aluminum alloy and a magnesium alloy, and to provide a micron three-dimensional double-bonded high toughness light alloy stock.

A three-dimensionally formed lattice body is installed in an ingot case or a ceramic mold. Further, the one forming fining crystal nuclei such as boron carbide is brought into reaction with molten metal directly before pouring, and pouring is performed, thus an internal structure is three-dimensionally formed in a belt shape to the gap direction of the three-dimensional lattice body. Further, rolling or press working is performed, so as to improve its toughness and strength.