The authors proposed a very large floating structure (VLFS) installing the oscillating water column (OWC) type wave energy absorption, and the response control on VLFS and the estimation of the electric power generation on OWC type wave energy absorption system were carried out. In the present, paper, a prediction method of electric power generation and also the photovoltaic power generation equipment was considered in order to carry out the examination of compound-type ocean wave power generator. A number of researches on the utilization system of natural environment energy in ocean have been performed. In general the electric power generation is calculated from the characteristics of generator, energy and rate of operation. In the present study, the system simulation method power generator of oscillating water column type by dividing into the primary and the secondary converters was adopted. The hydrodynamic forces on oscillating water column were calculated by three-dimensional singular distribution method, and the time history simulation on primary converter was carried out, . Secondary converter was expressed by using the equation of motion on turbine. Photovoltaic power generation used existing technique.