PURPOSE: To stabilize the mechanical quality of a forged part by blowing inert gas into a molten metal so that the content of gas in a forging stock becomes below a specific value, and subsequently, casting the forging stock from its molten metal and executing its forging.

CONSTITUTION: By blowing an inert gas such as Ar gas, etc. into a molten metal used for a forging stock, gas such as hydrogen gas, etc., melted in the molten metal is adsorbed to the inert gas. In this case, the content of gas in the cast forging stock is controlled so as to become ≤0.3cc/100g. Subsequently, this molten metal is poured into a mold at a prescribed temperature and a forging stock is formed, and thereafter, compressed and forged by a die and a punch and brought to plastic deformation, and a desired forged part is obtained. Since the content of gas in the forging stock is controlled to a sufficiently low value, the generation of a blow hole in the forged part is decreased remarkably. Accordingly, the mechanical quality of the forged part is stabilized.