Abstract: To expand the introduction amount of renewable energy，there are various problems such as suppression of output fluctuation, cost of compensation power supply for reducing output fluctuation, lack of transmission capacity．On the other hand， it is known that output fluctuation of renewable energy is leveled by interconnecting renewable energy in a wide area. In this research, propose a computer algorithm to optimize the introduction amount of each region and the capacity of the power supply for compensation from economical efficiency when dispersing solar power generation and wind power generation over a wide area using actual transmission network capacity Develop. Moreover， from the result, investigate the relationship between the expansion of the introduction amount of renewable energy and the capacity of the electricity transmission network．