A spot welding system including first and second spot welding robots, and a communication line connecting the first and second spot welding robots with each other so as to permit communication therebetween. The first spot welding robot includes a data transmitting section for transmitting welding data defining welding operations of the first and second spot welding robots through the communication line to the second spot welding robot, and a first control section for causing the first spot welding robot to perform a welding operation based on the welding data. The second spot welding robot includes a data receiving section for receiving the welding data transmitted from the data transmitting section of the first spot welding robot through the communication line, and a second control section for causing the second spot welding robot to perform a welding operation based on the welding data received by the data receiving section. The welding data may include welding condition data defining welding conditions under which the first and second spot welding robots perform the welding operations.