The present invention has an object of preventing segregation during the casting of Mg alloy or the like containing additive elements having a great difference of specific gravity to obtain a cast having a good quality.A casting mold 1 having a molten metal received therein is rotated in one direction by a rotary device 7 with the vertical axis as a rotary axis while solidifying the molten metal for a predetermined period of time, and, after the predetermined period of time is lapsed, the casting mold 1 is rotated in the direction opposite the direction of rotation for a predetermined period of time, and the rotation in the opposing directions is repeated so that the molten metal is solidified. The molten metal can be shaken and agitated without roughening the surface of the molten metal to uniformalize the distribution of temperature of the molten metal in the casting mold. The production of segregates can be minimized and a fine homogenous structure can be obtained. Thus, a metallic material excellent in ductility and strength can be obtained.