Sawayama Castle (Sawayama-jō) is a castle in the city of Hikone, Shiga Prefecture, Japan. This castle was an important military stronghold of Ōmi Province. The Azai clan held this castle in the Sengoku Period. Ishida Mitsunari held it at the end of the 16th century after the ruin of the Azai clan. This castle was attacked by Kobayakawa Hideaki after the Battle of Sekigahara. The castle surrendered at half a day though the brother of Mitsunari, Ishida Masazumi, defended it. Afterwards, Ii Naomasa occupied Sawayama Castle. However, he destroyed it, and moved to Hikone Castle.