A melting and holding furnace includes a main body and a material input mechanism supplying a molten metal to the body which includes a melting chamber; a molten metal receiving chamber; a pumping-out chamber; and a molten metal heating mechanism. The input mechanism includes a molten-metal surface level sensor to detect that the surface height position of the metal in the pumping-out chamber has reached a lower limit that is set to be above the lower surface height position of a lid of the melting chamber, and is set to supply the receiving chamber with the metal and/or the metal block when the sensor detects that the surface height position of the metal in the pumping-out chamber has reached the lower limit so that the surface height position of the metal in the pumping-out chamber is always kept above the lower surface height position of the lid.