A performance check method of earthquakeproof is proposed, based on the concent of energy balance between input energy and absorbed energy. The feature of this study is to be able to consider the rapidity of energy input by introducing the idea of "Energy Input Velocity". In this study, the destructive power of an earthquake is expressed by the quantity of the input energy and its input velocity. The seismic capacity of a building is expressed by the quantity of energy that can be absorbed within the continuation time of an earthquake on condition that the deformation is limited to the design maximum deformation. This is calculated by considering the balance between energy input velocity of the earthquake and energy absorption velocity of the building. Comparing this with the quantity of input energy caused by ground motion, the seismic safety is judged.
