To provide a method and a device for determining acceptance/rejection of the welding by a capacitor discharge type stud welding machine capable of determining acceptance/rejection of a stud by the stud welding by a method different from a conventional one.

In the method for determining acceptance/rejection of the welding in the capacitor discharge type stud welding machine, the upper and lower limit values of the current or the voltage with which the welding strength is permitted at three time points including the first reference time point at which a stud fore end tip part is melted, the second reference time point at which the arc is expanded outwardly from the stud center and the energy becomes its peak from the first reference time point, and the third reference time point at which a base material and the stud are welded to each other, are respectively determined to the welding condition to define a first determination area, a second determination area, and a third determination area. The current value or the voltage value in each determination area is measured for the actual stud welding, and the acceptance/rejection of the stud welding is determined based on whether or not the result of measurement is within the range from the lower limit to the upper limit of each determination area.