To solve a problem wherein slight amount of melted liquid leaks from a liquid drain port and is solidified before silicon raw material becomes melted liquid completely, thereby reducing yield.

The crucible 1 is composed of a melting crucible 1a and a holding crucible 1b, the melting crucible forms silicon melted liquid by heating and melting the silicon raw material 3 stored in the inside by a heating means 7, and the liquid drain port 4 for draining silicon melted liquid is provided in a bottom part of the melting crucible. The silicon melted liquid is supplied into a mold 8 provided in a lower part and is cooled/coagulated to obtain polycrystalline silicon ingot. The liquid drain port is closed from the outside using a plug body 2, which is dropped into the mold at predetermined timing to drain the silicon melted liquid.