An electrical resistance welding method was applied under atmospheric conditions by using a metal powder medium or media mixture which was sandwiched in the space between two metal bars which were compressed longitudinally, and simultaneously, current was conducted to generate Joule thermal heat. In the joining, aluminum was used as a base material and was joined to another aluminum, or one of four other metal bars with different melting points, by using resistance-welding apparatus. In the experiments, the specimens used as metal bars were aluminum, stainless steel, carbon steel, titanium and copper; and the powder media were aluminum, nickel and silicon. The reliability of the joined specimens was confirmed by their mechanical properties. In the present study, qualitative results are shown, but the best joining conditions are unknown, yet. However, it is concluded that the present method is useful for the joining of different metals, and it is of value to continue the investigation of joining by generated Joule thermal heat.