The purpose of this report is to describe the experimental results of dynamic lateral buckling behavior of T-shaped beams against impulsive load. Thin-walled beams are tested systematically in a pendulum type impact testing machine by changing geometrical parameters of specimens as well as loading conditions. Especially, we will study about dynamic loads and energy consumption, which are compared with static results. The present paper will also describe FEM model incorporating effects of increase of yield stress due to high strain rate in order to improve its capability for impact analysis. Based on numerical results by the present model, we will investigate experimental behaviors of the second lateral buckling mode as well as the first mode which cannot be conducted in the present testing machine.