To provide a welding device to be operated with a high frequency induction heating wherein a lowering of temperature due to blasting of an inert gas is prevented at a part to be welded and quality of welding/joining part is not deteriorated.

This is referred to a welding device being operated with a high frequency induction heating using a power source device 1 for a high frequency induction heating, a work 3 for high frequency heating and an inert gas generation device 5 such as a nitrogen or an argon gas. The device comprises an electromagnetic valve 7 installed between the work 3 for the high frequency heating and the inert gas generation device 5, a DC current detecting element 13 to detect a DC current of the power source device 1 for the high frequency induction heating, and an electromagnetic valve control circuit 20 to control an opening degree of the electromagnetic valve 7 depending on a size of an output signal from the DC current detecting element 13. Thereby, a flow rate of the inert gas being flowed into the part to be welded is controlled to be the best one, so that lowering of temperature due to a blasting of the excessive inert gas more than necessity can be prevented at the part to be welded, and deterioration of welding jointing part quality is also prevented.