In the previous report we presented a possible mechanism of fracture of nodular cast iron, founded on the dislocation theory and confirmed by the combined tension-torsion tests of ferritic nodular cast iron in liquid nitrogen. The present report first concerns the tension and torsion tests carried on the various types of nodular iron whose matrix is of ferrite with various grain sizes, of mixed structure of ferrite and pearlite, and of bull's eye structure. Through these experiments the authors have clarified the structural effect on the strength and ductility, which has proved to be consistent with the above theory. They also report the charpy impact tests on the same materials, with the results consistent with the formula induced from the above theory.