A distribution of wave power around Japan is estimated due to visual data of wave height for recent ten years in order to make it clear that wave energy is one of the important alternative clean energy for Japan. The linearized theory of wave power extraction of floating bodies is reviewed. It Includes fluid dynamic forces acting on floating bodies, motions, energy extraction and control of load damping. Lastly the present state of their development and probrems which should be solved for practical use are described.
