To reduce the amount of use of gas, and to improve work efficiency when brazing working is performed by using an inert gas such as a nitrogen gas at the time of the brazing working of piping.

Connectors CN1, CN2 are mounted on both ends of the piping to be brazed. The one-touch coupler CP2 of a main body unit IO is inserted into an output side connector CN2. A jetting nozzle NZ, a magnet MG and an exhaust port EX are provided in the main body unit IO, and a displayer L1 and a buzzer BZ are provided in the outside of the main body unit IO. A dry battery DR for driving the above displayer L1 and the buzzer BZ, a switch SW1 for driving power supply and a proximity switch SW2 are provided. The displayer L1 is lighted during the exhaust of air, etc., and the buzzer BZ sounds. By these mechanisms, the exhaust of the air, etc., in the piping can be confirmed by a workman even from a remote place. At the time when the supply of the gas has been stopped, the flowing out of the gas in The inside of the piping and the advancing of the air are prevented by the operation of the main body unit.