In a casting step, a first member is cast by die casting. In the driving step after the casting step, a self-piercing rivet is driven into, from a second member side, an overlapping part in which the second member overlaps the first member, while heat from casting remains in the first member. As a result, the self-piercing rivet is driven into the first member in a state that the ductility is higher than that at the normal temperature. Therefore, the first member is less likely to crack during the driving step.