The present invention relates to a welding device which includes a welding power source provided with a power supply circuit; a wire feeder connected to the welding power supply to supply wire; a torch which pulls the wire supplied from the wire feeder and supplies the wire to a welding part; an IR thermal camera which captures the welding part; a vision module having built-in program which receives and processes a captured image of a IR thermal camera; and a slag removal device which removes slag detected in the welding part in real time in conjunction with the vision module. The welding device has an effect in which slag generated during welding can be removed before the slag is fixed on the molten pool.