To determine the toughness of materials, Charpy V notch test has been widely utilized over the world. This method is easy to conduct, but obtained values are some what qualitative. Instrumented test has also a long history and gives us a loading history during impact. However this method is also still remaining in the range of a screening test. The author has successfully developed CAI ((C) under bar omputer (A) under bar ided Instrumented (I) under bar mpact Testing) System for the evaluation of dynamic fracture toughness. In this CAI system, dynamic fracture toughness parameters such as K-d, J(d) T-mat, and various absorbed energies can be obtained from the load-deflection curve of a single precracked specimen for both ductile and brittle materials.