Renewable energy from the ocean is important to solve the global environmental issues as well as to supply for their own country. There are several types of energy resources of the ocean including the tidal energy utilization with long experience. In addition, research of the wave power generation is expected and progressing for large scale. The next stage is to reduce the electrical cost by means of improving energy conversion efficiency, reducing the cost of the device and improving durability of the device intended for more than 100 years.