An electrode position control method according to the present invention includes a voltage detecting step of detecting voltages on a leading electrode and a trailing electrode that are brought into contact with a welding workpiece, a sensing step of detecting positional information of the welding workpiece from electrical changes in the voltages, a correction amount calculating step of calculating a correction amount for correcting for positional displacement of each of the leading electrode and the trailing electrode with respect to a weld line from the positional information, and a position correcting step of correcting the respective positions of the electrodes by adding or subtracting the correction amount.