To provide a connection structure of a gas pipe capable of facilitating connection work between both sides of one gas pipe and gas controllers and capable of reducing cost by reducing the number of components.

Extension pipe parts 13 extended to a gas pipe 1 are integrally formed on bodies 4 of both gas controllers 2, 3. Abutting parts 19 each having a shape corresponding to a peripheral wall of the gas pipe 1 and allowed to be abutted on the gas pipe 1 and cylindrical projection parts 20 are formed on tips of the extension pipe parts 13 of both the gas controllers 2, 3. A pair of hole parts 22 for inserting respective projection parts 20 are formed on opposite faces of the peripheral wall of the gas pipe 1. Flange parts 23, 24 projected from outer peripheral surfaces of the respective extension pipe parts 13 are formed so as to be opposed to each other when the abutting parts 19 are abutted on the gas pipe 1. The flange parts 23, 24 of the one gas controller 2 and the flange parts 24, 23 of the other gas controller 3 are coupled to each other by coupling members 27.