In a conventional arc welding robot control unit, since an emergency stop circuit for a robot and an emergency stop circuit for a welding machine exist independently of each other, not only the circuit configuration thereof is long but also the emergency stop enforcing processings and emergency stop removing processings are executed individually. To solve these problems, according to the invention, there is provided an arc welding robot control unit which comprises an inverter circuit 1 for enforcing arc welding, main power supply switches 2a-2c for turning on and off a main power supply used to supply power to the inverter circuit 1, a main power supply control part 3 for controlling the main power supply switches 2a-2c, and an emergency stop button 4 for emergency stopping the operation of a robot, wherein, when the emergency stop button 4 is depressed to thereby put the robot into emergency stop, the main power supply switches 2a-2c can be turned off in linking with the robot emergency stop.