Spot welding apparatus

A spot welding apparatus comprising:

• a first welding electrode;
• a second welding electrode disposed to face the first welding electrode, the second welding electrode being configured to clamp and press a workpiece together with the first welding electrode;
• and
• a sub pressure applicator including a sub pressure applying actuator and a sub pressure unit and being configured to move and selectively stop the sub pressure unit at a plurality of movement stop positions using the sub pressure applying actuator, the movement stop positions including a sub pressure position where the sub pressure unit is adjacent to the first welding electrode and in contact with the workpiece so as to apply a sub pressure to the workpiece, and a sub-pressure-non-requiring position where the sub pressure unit is located away from the workpiece;
• wherein sub-pressure-application spot welding and sub-pressure-application-non-requiring spot welding are executable, the sub-pressure-application spot welding being a process in which spot welding is performed by applying current between the first welding electrode and the second welding electrode while the workpiece is clamped and pressed between the first welding electrode and the sub pressure unit in the sub pressure position, which are in contact with the workpiece, and the second welding electrode, which is in contact with the workpiece while facing the first welding electrode, the sub-pressure-application-non-requiring spot welding being a process in which spot welding is performed by applying current between the first welding electrode and the second welding electrode while the sub pressure unit is held in the sub-pressure-non-requiring position and the workpiece is clamped and pressed between the first welding electrode, which is in contact with the workpiece, and the second welding electrode, which is in contact with the workpiece while facing the first welding electrode.