To make the molten metal tap flow amount adjustable in large quantity.

A copper-made crucible 2 provided with an induction coil 1 is composed of a plurality of segments 4 by means of slits 3. A material to be melted is placed in a crucible 2, and is leviated by electromagnetic repulsive force to be melted by induction heating, and molten metal 5 is obtained. In a fitting hole 2c provided in the bottom part 2a of the crucible 2, a plurality of cylindrical conductive adapters 8 with stepwise varying internal diameters of molten metal tap holes 6, 6a, 6b provided with a slit 7 are replaceably fitted. In this way, a molten metal tap flow amount is adjusted in a step of large amount, continuous casting of a cast piece and molten metal injection to a cast mold can be performed.