Abstract: An electric resistance spot welding device, comprising a pair of electrodes located on the same welding surface of an assembly to be welded. The assembly to be welded is provided with an axis of symmetry (6); the pair of electrodes are symmetrically disposed on two sides of the axis of symmetry; one end of each electrode has a special-shaped contact surface (20); the special-shaped contact surfaces are respectively offset in directions away from the axis of symmetry relative to the electrode axis, wherein the special-shaped contact surfaces are used for offsetting a current density centerline (21) formed by the electrodes in a direction away from the axis of symmetry relative to the electrode axis (11), and/or used for deflecting the tendency of the current density of each electrode away from a welding face within the assembly to be welded.