Hikone Castle (彦根城 Hikone-jō?) is an Edo period castle in the city of Hikone, in Shiga Prefecture, Japan. It is considered the most significant historical building in Shiga. Hikone is one of only 12 Japanese castles with the original keep, and one of only four castles listed as a national treasure.
Hikone Castle traces its origin to 1603 when Ii Naokatsu, son of the former daimyo Ii Naomasa, ordered its construction. The keep was originally built in 1575, as part of Ōtsu Castle, and was moved to Hikone by the Ii clan. Other parts of the castle were moved from Nagahama Castle. Hikone Castle was completed in 1622. Naokatsu's lands had been taken from him in the interval by the Tokugawa shogunate, and when his brother Naotake assumed control of the area around Ōmi Province, he was able to complete the castle by collecting stones from the former Sawayama Castle.