In the previous report, the plastic deformation behaviors of the model joints which were welded between 60 kg/mm² high strength steel (HT 60) and mild steel (SM 41) have been investigated under static tension parallel to the weld line. Because of the asymmetry of specimens, however, it is difficult to estimate from the above experimental results the plastic strain behaviors in the larger size of composite weldment. In the present research, therefore, are used the specimens of composite weldment in which HT 60 and SM 41 are symmetrically arranged about the axis parallel to the direction of tensile load. And strains which showed up in the specimens are experimentally analyzed by strain gages and Moiré method at the successive stages of loading in order to clarify the characteristics of the strain behaviors in the composite weldment consisting of dissimilar steels with different strength. The strains on the HT 60 side of the symmetric specimens of composite weldment do not concentrate so much as in the case of the HT 60 base metal, but rather turn up scattered at places far from the position of fracture initiation. The fact that the strains in that case increase to the same extent as those induced on the SM 41 side of composite weldment is also made known. A remarkable strain concentration is induced onto the HT 60 side of composite weldment after the maximum tensile load is reached, and the fracture is generated also on that same side.