The marine power plant is usually designed only from the standpoint of its steady state. However, the accurate knowledge of the kinetics of the marine plant is quite necessary for its advanced design, especially for its automation. The kinetics of marine boilers and turbines have been investigated by some of the authors, but the transient characteristics of a whole plant have not been studied yet. In this paper, the authors show the experimental results of the plant-kinetics as to a big steam tanker, which were measured during the starting, power change, astern-and inertia-tests. The test results are also analized with an analog computer. And it is confirmed that the marine steam plant can be simulated with a simple mathematical model.