To obtain a light-weight structural body having the firm rigidity and the high precision by welding crossing points of an end of an angle steel after assembling two sets of sub-assembly that a peak part of the angle steel and a steel plate are executed with resistance welding, to mutually cross the end parts of the angle steel.

Angle steels 1, 2 are arranged so as to mutually cross end parts E and welding parts are welded. The contact points of end part per each one of mutually crossing angle steels welded through a steel plate 3 and steel plate 4 and to them are formed at four places. The four places are pressurized, energized and welded at a time with paired electrode 7 and electrode 8, progressively, by executing this multi point welding, the laminate structural body is welded and assembled. Therefore, the light-weight structural body of honeycomb structure requiring the large rigidity and the high precision being used for the structure in the construction and the civil engineering, etc., can be realized.