It was the center of Imabari Domain under the Edo Period Tokugawa shogunate and was ruled by a branch of the HisamatsuーMatsudaira clan through most of its history.

The area of Imabari is in the center of ancient Iyo Province and strategic as the connection point between Shikoku and Honshu through the narrow channels of the Geiyo Islands.

During the Heian period, the area was a stronghold of Sumitomo no Fujiwara, who rebelled against the authority of the Emperor in Kyoto, and afterwards was dominated by the Murakami clan, a maritime clan who engaged in shipping or as pilots for vessels through the complex channels and rocky straits, but who also occasionally acted as pirates or as the mercenary naval force for a powerful warlord.

In the Sengoku period, the owed fealty to the Mōri clan, contributing greatly to them Battle of Miyajima, but their military activities were suppressed by Toyotomi Hideyoshi.

Only one yagura at the north corner of the Ninomaru enclosure was left, as it was used as an armory by the local army garrison, but when a fire broke out in 1871, the gunpowder inside ignited and exploded and the building was destroyed.

Imabari Castle features a vast seawater moat, a high stone wall and a rare style of main gate.

The Kurogane-gomon and Bugu-yagura turrets have been reconstructed also with interior and a small exhibition including a model and various videos explains their function and the castle's history.