A gas fuel supply apparatus includes: first and second mouthpiece attachment sections capable of detachably attaching thereto mouthpieces of first and second gas containers and provided in communication with each other; and first and second check valves provided in a communication passage, communicating between the mouthpiece attachment sections, in corresponding relation to the first and second gas containers. The first and second check valves prevent a gas fuel, let out from any one of the first and second gas containers, from flowing into the other of the gas containers.