A conduit for molten glass, a molten glass degassing method and a sub-atmospheric apparatus are provided, which are able to produce homogenous and good quality glass at low cost. A conduit for molten glass 20, which is capable of flowing molten glass 21 in a horizontal direction, and to which vertical pipes 22 are connectable, is disposed in a substantially horizontal direction. The conduit for molten glass 20 can increase the area of a free surface 26 of the molten glass by setting a width W at a larger value than a height H in cross-section and having an outline in cross-section comprising a convex curve. When the conduit for molten glass 20 thus configured is used as a sub-atmospheric apparatus 10, it is possible to degas the molten glass effectively. Additionally, it is possible to have a sufficient strength since the convex curve forming the cross-section is elliptical. Further, it is possible to reduce costs by decreasing the amount of metal required for forming the cross-section.