PURPOSE: To subject a semisolidified metal to degassing treatment and to cast it with excellent fluidity in a mold, at the time of casting a semisolidified metal in a state where solid and liquid are coexistent in a mold, by charging the mold to a container in a state of reduced pressure and controlling its atmospheric pressure.

CONSTITUTION: The molten metal 6, e.g. of an Al allay in a ladle 5 is fed into a receiving tank 1 via a tundish 10, is held in a molten state by an induction heater 13 and is thereafter cooled by a water-cooled jacked 8 in a cooling and stirring tank 2 at the lower part into a slurried semisolidified metal in which a solid phase and a liquid phase are coexistent, which is thereafter subjected to intensive stirring by a stirrer 3 to refine the grain size of the solid phase metal as well as to uniformize the mixed state of the solid phase and the liquid phase. An exhaust port 11 at the bottom of the cooling and stirring tank 2 is airtightly connected to a pressure reducing tank 14, and the atmospheric pressure in the pressure reducing tank 14 is controlled by a pressure regulating valve 17, by which a slurried semisolidified metal 8 having a high solid phase rate and in which the solid phase metal is finely and uniformly mixed can be cast with excellent fluidity in a mold 20, so that a casting of high quality can be manufactured.