PURPOSE: To uniformly disperse fine compound in molten metal and to improve the strength by blowing gas generating the fine compound by reacting with the molten metal after mixing in high pressure gas, laminating fine droplet containing the fine compound and solidifying.

CONSTITUTION: Aluminum or rare earth element is melted beforehand in the molten metal and at the time of solidifying as laminating the molten metal flow as dispersed droplet by blowing the high pressure gas to the molten metal flow, the molten metal is solidified as laminating, under condition of forming fine oxide grain by reacting oxygen suitably mixing in the high pressure gas with the aluminum or rare earth element. Then, the strengthened material uniformly dispersing fine oxide grain of fine aluminum or rare earth element, is obtd.