An object is to provide a gas bushing that makes it possible to improve withstand voltage characteristics in the surrounding of a metal flange 4 and to inhibit partial electric discharges or flashovers. The gas bushing includes: a hollow insulator 1 of which the inside is filled with electrically-insulating gas; a center conductor 2 extending through the inside of the hollow insulator 1; and the metal flange 4 made of metal and provided at an upper end of the hollow insulator 1. The center conductor 2 includes: a main electrically-conductive portion 2b having a first outside diameter; and a larger-diameter portion 2a being provided in an upper end portion of the center conductor 2 and having a second outside diameter that is larger than the first outside diameter. A lower end 2c of the larger-diameter portion 2a is positioned lower than a tip end portion 4a of the metal flange 4.
