Abstract: A resistance welding process for aluminum and aluminum alloy materials for enabling the remarkable improvement of the electrode life comprises the steps of preparing an insert material having the overall thickness of 0.02 to 1 mm including a sheet-like core material consisting of iron, steel, copper or copper alloy and coated layers each having the thickness of 1 to 100 .mu.m, consisting of any one of Ni, Ni alloy, Ti, Ti alloy, Nb, Nb alloy, Mo, Mo alloy, W, W alloy, Cr, Cr alloy, Co and Co alloy and formed on both surfaces of the core material, or an insert material consisting of Ti foil or Ni foil; interposing the insert material between each of upper and under electrodes and each portion of overlapped materials to be welded consisting of aluminum or aluminum alloy; pressurizing the materials to be welded by the upper and under electrodes to join the materials to be welded together. The coated layers on both surfaces of the core material may consist of the same metal or different metals from each other.