The imposing offshore gate of a UNESCO World Heritage shrine in Japan's western prefecture of Hiroshima has been restored to its former glory.

The Otorii gate, measuring 16 meters tall and 24 meters wide, stands in the sea a short distance from the main hall of Itsukushima Shrine in the city of Hatsukaichi. The Shinto shrine was rebuilt in the 12th century.

Work to repair and preserve the gate took three and a half years. It was the first such large-scale project in about seven decades.

Workers reinforced the gate's earthquake resistance while artisans rethatched its roof and repainted its vermilion pillars.

The gate is now visible in its entirety after scaffolding and protective nets used for the restoration program were removed.

About 30 people celebrated the completion of the project during a Sunday ceremony, which featured a ritual to purify the gate.

A civil engineer involved in the project said he is pleased to have helped to repair the gate together with other technicians despite greater-than-expected damage to the structure.

A member of the shrine's clergy said he hopes people will visit and see the gate to ring in the New Year with blessed feelings.