A method of manufacturing glass, comprising: a melting step for melting a glass material and obtaining molten glass; a stirring step for stirring the molten glass obtained in the melting step; and a forming step for forming glass from the molten glass stirred in the stirring step; wherein the stirring step comprises a first stirring step in which the molten glass is stirred while being directed upward from below in the interior of a first stirred tank, and a second stirring step in which the molten glass stirred in the first stirring step is stirred while being directed downward from above in the interior of a second stirred tank; the first stirred tank comprises a first chamber and a first stirrer for stirring the molten glass in the first chamber, the first chamber communicating with an upstream conduit attached to the side wall at the bottom of the first chamber and with a connecting pipe attached to the side wall at the top of the first chamber, and the upstream conduit being configured such that the molten glass flows into the first chamber in the lateral direction; the second stirred tank comprises a second chamber and a second stirrer for stirring the molten glass in the second chamber, the second chamber communicating with the connecting pipe which is attached to the side wall at the top of the second chamber, and with a downstream conduit attached to the side wall at the bottom of the second chamber, and the downstream conduit discharging the stirred molten glass from within the second chamber in the lateral direction; the upper lateral part of the first stirred tank is connected by a connecting pipe to the upper lateral part of the second stirred tank; and the molten glass is transferred from the first stirred tank to the second stirred tank via the connecting pipe; characterized by discharging the molten glass from the bottom of the first chamber through a first discharge pipe attached to the bottom face of the first stirred tank; and discharging the molten glass from the liquid level of the molten glass in the second chamber through a second discharge pipe attached to the side wall at the top of the second stirred tank. a melting step for melting a glass material and obtaining molten glass; a stirring step for stirring the molten glass obtained in the melting step; and a forming step for forming glass from the molten glass stirred in the stirring step; wherein the stirring step comprises a first stirring step in which the molten glass is stirred while being directed upward from below in the interior of a first stirred tank, and a second stirring step in which the molten glass stirred in the first stirring step is stirred while being directed downward from above in the interior of a second stirred tank; the first stirred tank comprises a first chamber and a first stirrer for stirring the molten glass in the first chamber, the first chamber communicating with an upstream conduit attached to the side wall at the bottom of the first chamber and with a connecting pipe attached to the side wall at the top of the first chamber, and the upstream conduit being configured such that the molten glass flows into the first chamber in the lateral direction; the first chamber communicating with an upstream conduit attached to the side wall at the bottom of the first chamber and with a connecting pipe attached to the side wall at the top of the first chamber, and the upstream conduit being configured such that the molten glass flows into the first chamber in the lateral direction; the second stirred tank comprises a second chamber and a second stirrer for stirring the molten glass in the second chamber, the second chamber communicating with the connecting pipe which is attached to the side wall at the top of the second chamber, and with a downstream conduit attached to the side wall at the bottom of the second chamber, and the downstream conduit discharging the stirred molten glass from within the second chamber in the lateral direction; the second chamber communicating with the connecting pipe which is attached to the side wall at the top of the second chamber, and with a downstream conduit attached to the side wall at the bottom of the second chamber, and the downstream conduit discharging the stirred molten glass from within the second chamber in the lateral direction; the upper lateral part of the first stirred tank is connected by a connecting pipe to the upper lateral part of the second stirred tank; and the molten glass is transferred from the first stirred tank to the second stirred tank via the connecting pipe; characterized by discharging the molten glass from the bottom of the first chamber through a first discharge pipe attached to the bottom face of the first stirred tank; and discharging the molten glass from the liquid level of the molten glass in the second chamber through a second discharge pipe attached to the side wall at the top of the second stirred tank.