WELDING SYSTEM, CONTROL DEVICE, CONTROL PROGRAM AND WELDING METHOD

The present invention can automatically calculate the location of a positioner when the same is holding a workpiece, and improves work efficiency by automating work to determine the location of the positioner. Provided is a welding system (1) which uses a welding device (30) and a positioner (40) to weld a workpiece (W), and has a control device (50) controlling the welding device (30) and the positioner (40). The positioner (40) comprises: a workpiece location setting mechanism (41) which has reference location information; and at least one holding mechanism (10) which holds the workpiece (W). The control device (50) has a positioner location calculation means (51a) which, on the basis of the reference location information received from the workpiece location setting mechanism (41) and workpiece information inputted into the control device (50) in advance, calculates the location of the holding mechanism (10) when the same is holding the workpiece (W). 能够自动地计算把持工件时的定位器的位置，使定位器的定位作业自动化而实现作业效率的提高。使用焊接装置(30)及定位