An apparatus for manufacturing a float glass, including a float bath for strong a molten metal on which a molten glass flows, wherein the molten metal flows in the float bath, comprises a plurality of discharge slits formed through a wall of a downstream end of the float bath to discharge a molten metal crashing against the wall and dross floating on the molten metal; a flow-back channel formed in a widthwise direction of the float bath and communicated with the discharge slits; and a dross collecting member for collecting the dross flowing through the flow-back channel.