Okioshio Castle (置塩城, Okioshio-jō) is the remains of a Muromachi period Japanese castle structure located in the city of Himeji, Hyōgo Prefecture, Japan. Its ruins have been protected as a National Historic Site as one of the Remains of Akamatsu-shi Castles, combining both Shirahata Castle and Kanjōsan Castle, since 1996. It is also referred to as "Ojio Castle" after an alternative pronunciation of the kanji in its name.