Abstract: A welding core wire supply device comprises a conduit containing a welding core wire guide tube, a control cable, a power cable and so forth therein and having connectors at its both ends, a given number of supply units each having a supply section for leading and supplying a welding core wire to a desired zone of the conduit, and a power unit. The plurality of supply units are serially connected to the power unit through said connectors. Each supply section comprises at least a pair of rollers for drawing the welding core wire therebetween, a pull motor for rotating the rollers, a control device for controlling the pull motor with constant torque and a circuit for turning on and off a power supply to the supply units in response to welding start, stop and inching signals.