Carbon fiber reinforced plastic (CFRP) laminates are used in the wide field, because they have excellent properties of a specific strength and of a specific stiffness. The CFRP has a possibility of weight reduction automotive structures which can contribute to improve mileage and then to reduce Carbon dioxide. On the other hand, the safety of collision should be also made clear in the case of employing the CFRP to automotive structures. In this paper, the Al guarder beam reinforced with the CFRP is examined by an experiment and by a numerical analysis for replacing it to the conventional steel door guarder beam equipped in the automotive door. The experimental relations of impact load to displacement for the Al guarder beams with the different thickness of CFRP showed the good agreement with those of numerical results. From the comparison of these results, the numerical method developed here is quite useful for estimating the impact behaviors of Al guarder beam with CFRP layer.