It is important to obtain the damping ratio of equipments and buildings of Nuclear Power Plant when they are subjected to external forces such as earthquakes. The equipments of Nuclear Power Plants are on a very large scale and have complicated structures and non-linear characteristics. So, it is very difficult to estimate the damping ratio of these equipments. This paper mainly presents the view of the studies of damping characteristics of these equipments of Nuclear Power Plants. The studies of vibration control and vibration isolation which are strongly related to damping have become popular recently and the results obtained from these studies are applicable to the equipments and builidings of Nuclear Power Plant. This paper also presents the view of recent studies and future subjects of vibrations control and vibrations isolation of the equipments and buildings mainly concerned with the Nuclear Power Plant.