Abstract: A stud welding device may include: a gun frame; a transformer disposed at a side of a rear portion of the gun frame and supplying welding current; a pressing cylinder mounted at a front portion of the gun frame and including an operating rod; a cooling holder mounted at a front end of the operating rod of the pressing cylinder; a stud welding tip mounted at a front end of the cooling holder and formed of an inserting hole in which negative pressure is applied; and an electric cable connected to one side of the operating rod of the pressing cylinder and applying the current of the transformer to the stud welding tip, wherein the stud welding device is adapted to execute resistance welding by applying pressure and the current to the base metal in a state of mounting a stud bolt at the stud welding tip using the negative pressure in the inserting hole.