The sea-borne shrine that Taira no Kiyomori deeply revered and rebuilt in its present splendor as the tutelary shrine of the Taira clan. A World Heritage site, it preserves treasures such as the Heike Nokyo sutras that symbolize Kiyomori's power.

Around 1168, Taira no Kiyomori, serving as Governor of Aki, designated Itsukushima Shrine the tutelary shrine of the Taira clan and built the over-the-water shinden-style complex still seen today. His eldest son Shigemori (1138-1179) had by then risen to Inner Minister and was the Taira clan's second-in-command after his father, supporting the family's devotion to Itsukushima. The 'Heike Nokyo' sutras (National Treasure) dedicated by Kiyomori included sutras copied by Shigemori and other clan members. The shrine that father and son venerated as the Taira clan's guardian deity now enshrines the glory of the Heike as a UNESCO World Heritage Site.

In 1555, Mori Motonari staged the Battle of Itsukushima on this very island, luring Sue Harukata into a trap and annihilating his force. Motonari drew the 5,000-strong Mori army onto the island fortress, then launched a surprise amphibious assault through a storm to destroy the 20,000-strong Sue army. Counted among Japan's three great surprise attacks, this victory was the turning point that made the Mori clan masters of the Chugoku region.