A Tokugawa adminastrator, Ii Naosuke received it as a fief from Tokugawa Ieyasu for his work in the Battle of Sekigahara. Since he died in 1602, his son, Ii Naotsugu took over the work and completed the castle in 1622.

Tokugawa's policy of destroying all castles except for one in each feudal domain led to the building of this castle. Many gates and yagura from the remains of the destroyed castles were used in the Hikone. These castles include the Sawayama, Otsu, and Kotani.

The tenshu of the Hikone Castle was originally five floors and part of the Ostu Castle. After it was destroyed, the tenshu was removed and went to the Hikone Castle with three floors. Having only three floors, it was considerably small. The different sized windows built on the walls of the tenshu made the interior of the tenshu full of light. Some of the windows near the upper part of the tenshu are lotus-petal shaped. This unusual shape adds to the beauty and uniqueness of the castle. The roof gables also added to the complexity of the small tenshu.

There are three moats surrounding and within the castle grounds with each one surrounded by a thick wall. They were so heavily fortified and protected that there were watchtowers for each moat. In the grounds within the inner moat was where the high officials and samurai lived. The largest population in the Hikone Castle grounds lived in its southern areas. Because of this, many new crafts developed.