Funai Castle (Funai-jō) is a 16th century castle, located in Ōita, Ōita Prefecture, Japan. It was built by Otomo Sorin in 1562, who owned much of the surrounding Kyūshū island. The castle was originally built with several turrets (yagura), all of which were burnt down with the three story donjon in 1743. The covered bridge that led to the castle over its moat, as well as several turrets, have been rebuilt in modern times. Original remains include part of the wall and the moat itself.