To adjust the position of the height of a lower electrode rapidly and correctly by automatically moving and adjusting to the welding position in exchanging the lower electrode, in a resistance welding machine provided with a rotatable and disclike upper electrode and a lower electrode.

In exchanging the lower electrode 3, a driving motor 14 of a lifting driving device 13 is driven to lower the center of the lower electrode 3 to the reference position, the peripheral position of the new lower electrode 3 after the exchange is measured by the measuring device 26A, on the basis of the measured value and the distance from the center of the lower electrode 3 in the reference position to the height of the position of the upper edge of the peripheral face of the lower electrode 3 in the prescribed welding position, the raised amount of the lower electrode 3 is calculated, and on the basis of the calculated value, the driving motor 14 of the lifting driving motor 13 is reversely driven to lift the new lower electrode 3 to the specific welding position.