Abstract: The present invention is a silicon refining apparatus including, in a reduced pressure vessel: a crucible capable of holding molten silicon; a heat-retaining lid capable of being placed over the crucible; and a heating device. The crucible has a lateral outer-circumferential portion provided with a first thermal-insulation material. The heat-retaining lid is a plate-like member made of carbon felt and provided with a carbon composite material at least on opposed main surfaces. The heat-retaining lid has opposed main surfaces with an opening formed to extend therethrough. The carbon composite material on the main surface of the heat-retaining lid on the crucible side is so placed as to cover an upper surface of the first thermal-insulation material when the heat-retaining lid is placed at an upper surface of the crucible.