To provide a glass melting furnace of optical glass, in which a glass melting tank is sealed in an openable manner to prevent a gas generated in the furnace from flowing out of the furnace.

In the glass melting furnace provided with the melting tank for melting a glass material, the upper part of the melting tank is opened, and a lid is detachably mounted on the upper part of the opened melting tank to close the upper part. The lid is mounted on the upper part of the melting tank such that it is inserted into a sealer which liquefies at least during the melting of the glass material to seal the melting tank.