To adjust the sharing degree of the opening allowance of two gun arms by surely performing the pressing or opening motion between electrode tips.

A multi-spot welding machine is provided with a movable side gun arm 12 having an electrode tip, and a fixed side gun arm 2 having an electrode tip 3, the gun arms are turnably connected to each other by intermediate links 16, 17 through connection pins A and B, the gun arm 12 is connected to a rod 15 for driving a pressing actuator 4 through a connection pin C, the gun arm 2 is integratedly with the actuator 4 side, and the actuator 4 is movable through an equalizer mechanism 7. The axis D is parallel to the axis of pressurization E, the line × connecting the pressing position between the electrode tips to each axis of the connection pins A, C is orthogonal to the axis of pressurization, the center line F of the actuator is parallel to the axis, and locking plates 20, 21 to actuate the equalizer mechanism by regulating the opening stroke of the of the gun arm 12 in an abutted manner on stoppers 18, 19 provided on a fixed bracket 10 of the equalizer mechanism, is fitted in an attachable/detachable manner to/from the connection pin B.