Fracture phenomena and energy-absorbing capacity of a thin metal sheet under penetration by a 20.5 mm-diameter cylindro-conical projectile are studied experimentally. The top angle of the projectile is 45 degrees, and the diameter of the top spherical surface is 5.5 mm. The materials of the sheet used in this study are Extra Super Duralumin (7075-T6), Corrosion-resisting Aluminium Alloy (A 5083 P) and Cold Rolled Carbon Steel (SPCC), whose thickness and diameter are 1.0 mm and 200 mm, respectively. On SPCC and A 5083 P, the Energy-absorbing Capacity UT is almost equal to the energy of crack extension and dynamic UT is about twice that of the static one. However, on 7075-T 6, the energy of petal bending is half as much as UT and dynamic UT is equal to the static one.