Japan is the maritime state surrounded by the sea, effective use of the ocean energy which exists abundantly is an important issue, and the realization is desired. Tidal current is the periodic energy which can be predicted, therefore it can expect to supply energy stably. In Seto Inland Sea, many straits and Seto regions exist, and it is known that tidal current energy will be amplified because a tidal current becomes quick. Therefore, the power generation technology which utilized current energy attracts attention. This study estimated the possibility of the tidal current power generation in Seto Inland Sea by performing local observation. At first time, the amount of maximum energies was calculated by observing the tidal current of Seto Inland Sea. Next, the amount of maximum energies obtained when a dynamo is built was calculated.