A vacuum degassing apparatus having a throughput of at least 200 tons/day without causing problems such as a stagnation of molten glass flow in the molten glass flow path, an increment of flow rate of the molten glass flow in a local area, an excessive increment of pressure loss of the molten glass flow.A vacuum degassing apparatus comprises a vacuum degassing vessel, and an uprising pipe and a downfalling pipe which are connected with the vacuum degassing vessel, wherein the vacuum degassing vessel includes a wide portion for providing a molten glass flow path, and in the wide portion, the proportion W1/L1 of the breadth of molten glass flow path W1 to the length of molten glass flow path L1 is at least 0.2 and that in the vacuum degassing vessel, the breadth of molten glass flow path W2 of the portion connected with the uprising pipe and the breadth of molten glass flow path W3 of the portion connected with the downfalling pipe are narrower than the breadth of molten glass flow path W1 in the wide portion, and the position of the bottom of molten glass flow path of the portion connected with the uprising pipe and the position of the bottom of molten glass flow path of the portion connected with the downfalling pipe are lower than the position of the bottom of molten glass flow path of the wide portion.