The square section tube was axially compressed under the dynamic condition exhibiting a progressive buckling pattern with multi lobe. The onset of the first buckling was controlled by the inertial effect arising immediately after the impact, in which the inertia force was induced by the solid mass attached to the tube wall. Impact experiment with the aid of drop-hammer and the corresponding numerical simulation were conducted. Experimental observation with a high-speed video camera and the numerical simulation revealed that the control by the inertial force was successful.