PURPOSE: To obtain the desired and stable welding quality wherein any one of plural joints does not exert any influence upon welding of other joints by a method wherein each strap is provided with a joint and respective joints facing each other through a partition are connected to each other, by resistance welding.

CONSTITUTION: In case adjacent cells are connected to each other, joints 7 and 7', 8 and 8' are fitted in a hole 3 of a partition 2 from both sides, the respective joints facing each other, namely, the joints 7 and 8 as well as the joints 7' and 8' are respectively brought in contact with each other in the hole 3 to allow conduction of a resistance welding current for welding connection between 7 and 8, followed by welding connection between 7' and 8' by the same method. Thereby the order of welding between the joints 7 and 8 as well as the joints 7' and 8' shall be arranged in such a way that the respective straps are electrically isolated because it is so composed that the positive electrode strap is divided into 5 and 5' while the negative electrode strap is divided into 6 and 6'.