This paper describes present situation and future prospects on design input earthquake motions for tall buildings and base-isolated buildings. We investigated input earthquake motions those had been used for seismic design of specific buildings in the Kanto plain. Consequently, we point out a fact that natural periods of tall buildings distributed avoiding the peaks of input motions such as El Centro 1940, Taft 1952 and Hachinohe 1968 before the Hyogoken-nanbu earthquake. But after the earthquake, this tendency seems to have been improved by simulated earthquake motions. It's important to design these buildings by using the input earthquake motion with long period considering underground structure.
