PURPOSE: To enable fusing conditions to be easily set in connecting both electrode poles of plate groups, which are adjacent to one another with a container partitioning wall provided between them, by a resistance welding, and reduce the variation of the fusing intensity by automatically cutting of a welding current by detecting elastic waves produced during the welding.

CONSTITUTION: Plate groups 3 and 3' are installed adjacently to one another with a container partitioning wall 1 provided between them. At the same time, welding electrodes 5 and 5' are made in contact with the back surfaces of electrode poles 4 and 4'. After that, when electrodes 5 and 5' are energized while being pressed toward the wall 1, parts of the poles 4 and 4' which are in contact with one another with a penetrating hole 2 provided between them are fused together, and a kind of elastic waves are produced in accordance with the above fusion. A welding current is automatically cut off by detecting thus produced elastic waves with a microphone 7, and operating relay 6 by amplifying the waves with an amplifier 8. Since a welding current is automatically cut off by detecting elastic waves produce during the welding as mentioned above, the welding can be performed by setting only such welding conditions as a current value and a pressing pressure. Besides, since the current applied time can be automatically adjusted to the optimum, the variation of the fusing intensity is reduced.