PURPOSE: To prevent the generation of crack by forming a joining extending in the thickness direction at, at least one sheet is joined, making resistance spot welding while the surrounding part of the joining hole is pressurized by an electrode when two metallic sheets are resistance spot welded.

CONSTITUTION: Aluminum alloy sheets 1 and 2 are pressurized by the upper and lower electrodes 8 and 9. The axial centers of the electrodes 8 and 9 and through holes 3 and 4 as joining holes are coincident and the surrounding parts of the through holes 3 and 4 are pressurized by the electrodes 8 and 9. Then, the joining parts are melted by a applying a welding current 1-1 between both electrodes. Thus, even when a metallic material having a high coefficient of thermal expansion is joined, the amount of strain caused by solidifying shrinkage is small to make the tensile stress generated at the joined part small. Consequently, the generation of crack caused by solidifying shrinkage at the joined parts is prevented, grinding of the surfaces of electrodes is reduced and the welding work efficiency is improved.