(57) An automatic molten metal supplying device capable of supplying the molten metal within a short period of time with maintaining accuracy in supplying amount and without any dripping of the molten metal from a ladle and without any temperature decrease of the molten metal in the ladle during its transferring state even if the transferred molten metal has a small volume. A molten metal intake/discharge port is formed at a bottom portion of a ladle, and atmosphere communication/blockage unit is provided which selectively communicates an internal space of the ladle with an atmosphere. After the molten metal is introduced into the ladle through the intake/discharge port, the space is shut off from the atmosphere. A cross-sectional area of the intake/discharge port is in a range of from 20 to 80 mm². Lower limit of the cross-sectional area of the intake/discharge port is still sufficient to allow the molten metal to be flowed into the ladle, and upper limit thereof is sufficient to prevent the molten metal in the ladle from being dripped therefrom. Thus, small amount of the molten metal can rapidly and accurately casted.