To provide a spot welding machine that can automatize and robotize a welding operation itself in spot welding employed in the field of metallic sheet machining in small quantities.

The spot welding machine is equipped with a table electrode 110 that is composed of a flat electric conductive material to operate as a lower electrode and with a portal frame body 120 that is nearly horizontally installed on this table electrode 110. In the portal frame body 120, there is provided a welding gun 130 that performs resistance welding as an upper electrode by holding a workpiece between it and the table electrode 110, freely movably in the height direction with a vertical posture maintained. In the welding gun 130, a rotating device 140 is provided that rotates at least the lower end. Furthermore, the portal frame body 120 is configured to be freely movable in the longitudinal direction along the table electrode 110 as well as in the width direction thereof.

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