To provide a method and a device for the series spot welding, by which defective welding does not occur.

The applied current of initial welding is made two times a steady state current and the pressurizing forces of electrode tips 30A and 30B to plates 40 and 44 are made 1.25 times steady state pressurizing forces. That is, by increasing the pressurizing forces in the initial welding, the contact resistance of the plates 40 and 44 is decreased. Simultaneously with that, by making a high current to flow, the current is made to flow through the plate 44 on the opposite side of the electrode tips, and weld nuggets are produced at contact points of the plates 40 and 44. And, after the weld nuggets is produced once, the steady state current is made to flow, and by decreasing the pressurizing forces, the weld nuggets are grown up, and both plates 40 and 44 are welded.