In this paper, the energy absorption characteristics on extruded aluminum box-section strengthened with carbon-fiber-reinforced plastics (CFRP) laminates and/or foam material were investigated under impact loading. Impact tests using a pneumatic impact tester were conducted with the specimens in three-point bending flexure with consideration given to the side-door impact beams in vehicles. The absorbed energy to the specimen during the impact was determined from the loaddisplacement curve, which was obtained from the strain gauge attached to the impactor and the laser displacement transducer. From the results, it was found that the strengthening by externally bonding with CFRP laminates improved the impact-induced energy absorption. Also, the effect of the improvement was clearly seen in the case of the use of filling form material in the aluminum extrusion together with attaching CFRP laminates.