The statical penetrating tests on two 1/15 scaled solid bow models (bulbous stem and vertical stem) of 100, 000 ton tankers against same scaled side tank models of 400, 000 ton tankers were carried out. As the results of the experiments, it was clarified that a strut and its adjoining structural members such as shell plate, transverse ring and horizontal girder which withstand the collapse of the strut have the largest portion of whole resistive force against the penetration. Under the assumption that a strut and its adjoining members maintain constant resistive force after the collapse and a few assumptions that were already presented by Dr. Y. Akita and others, we obtained a method of calculating approximately the relation between load and amount of penetration. The calculated energy absorbed during the collision was less than that experimented by about 10%.