Method of the resistance spot welding dissimilar metal material

PROBLEM TO BE SOLVED: To provide a resistance spot welding method of dissimilar metal materials capable of securing bond strength.SOLUTION: When performing resistance spot welding by sandwiching with a pair of electrodes in the state where plate materials are superposed mutually, and by energizing the electrodes, a current is supplied by repeating increase/decrease of the energization amount intermittently in a plurality of steps. As for each step, materials are softened in step A, each dissimilar metal material is stuck to each other by energization in step B, and nuggets are generated or increased and welded in step C.