A device for low-pressure casting wherein the stalk or the guiding tube is filled with inert gas by causing the space formed over the molten metal in the pressurizing room to communicate with the stalk or the guiding tube. The device for low-pressure casting (100) wherein molten metal is supplied into a mold through a stalk (8) suspended from a gate for pouring of the mold (7) or through a guiding tube (21) connected to the gate for pouring at one end by pressurizing the molten metal by inert gas, the device including: a room for holding molten metal (1); a pressurizing room (2) to be in communication with the room for holding molten metal through a hole for communication (4), wherein a bottom end of the stalk (8) enters the pressurizing room or an opposite end of the guiding hole is connected to the pressurizing room, and wherein the molten metal is pressurized by inert gas; an on-off valve (5) for opening and shutting the hole for communication; a sensing device (15) for sensing that the space over the molten metal in the pressurizing room communicates with the stalk or the guiding tube; and a device (30) for supplying inert gas to an upper part of the pressurizing room.