The main research field in the structural dynamics & vibration control laboratory are dynamic analysis and seismic analysis and vibration control of large structure such as bridges, buildings. and nuclear power plants. This laboratory has an efficient technique for eigenvalue analysis, which is one of the most important steps when dynamics analysis is performed by the mode superposition method. New algorithms for eigenvalue sensitivity analysis and an optimization technique were also developed in this laboratory. We are currently developing improved vibration controllers and an earthquakes. Moreover, design for composite material structures and an overall system for the diagnosis, repair, maintenance, and management of bridges have been investigated.