For the purpose of developing tidal power generation using bridge pier, we conducted tidal current observation and calculated the amount of energy that can be acquired by assuming the power generation facility specifications. As a result of the tidal current observation for the Oshima Ohashi bridge, the maximum power generation output shows a value of about 120 kW, and the maximum power generation amount of the day got about 330 kWh/day. This value is about one-third of the initial forecast, and the main reason for this is the fact that after the current was formed at the generator installation site due to the vortex generated at the upstream piers at the time of downward tide, It was suggested that it becomes smaller.