Abstract: A resistance welding electrode includes a barrel-shaped portion having a cooling water passage defined therein and extending closely to an end surface thereof, and a cylindrical projection integrally formed on the end surface of the barrel-shaped portion. The cylindrical projection has a helical groove defined therearound, and may additionally have another helical groove defined therearound parallel to the first-mentioned helical groove in 180.degree.-out-of-phase relation thereto. The cylindrical projection may have an axial slot defined in its circumferential surface across the helical groove.