Okunoshima War Ruins

Completed in 1988, this museum was built to pass down the tragic history of secret poison gas production on Okunoshima and the realities of the war to future generations. It displays valuable materials regarding the damage caused by gas production and the island’s past as a place erased from maps, serving as a place of learning that reaffirms the importance of peace. This is the first place you should visit when touring the ruins.

This was a sturdy, camouflaged trench built to prepare for enemy air raids. It housed an automatic telephone exchange for use in emergencies. The yellow and green concrete that remains today shows how the camouflage looked at the time.

This monument contains a register of the names of people who died while engaged in the dangerous and harsh production of poison gas or post-war disposal. A memorial service is held every October to vow that such tragic damage will never be repeated. Next to the cenotaph is a declaration inscribed with the thoughts of those who passed away from poison gas-related illnesses.

When the poison gas factory opened in 1929, employees restored a shrine that was located near the current Kyukamura lodging, renamed it “Okunoshima Shrine,” and moved it to its current location. Various events (such as Kigensetsu and Tenchosetsu) and ceremonies (such as entrance and graduation ceremonies) were held on the grounds. In 1937, a monument to those who died during poison gas production was erected within the shrine precincts.

Initially just a small clinic, an inpatient ward was built around 1937, and it became a full-scale hospital with departments for dentistry, internal medicine, surgery, ophthalmology, and otolaryngology, as well as an X-ray room, a poison gas treatment room, and wards (30 beds). Today, it is a plaza in front of the swimming beach, and water faucets used at the time still remain.

Stone pillars inscribed with phrases like “Army Jurisdiction” remain near the stone steps leading to the lighthouse. These indicate that after the island became military land, the lighthouse and the poison gas factory grounds were strictly separated by barbed wire.

This is where a searchlight was placed during the Geiyo Fortress era (around 1904). Its role was to illuminate the sea surface at night to detect enemy ships. Today, the light well and the room below remain.

During the war, about 50 air-raid shelters were dug on the island. They were created to store poison gas and related materials, and stone-lined entrances can still be seen in various places across the island today.

The white building was the “Laboratory” where poison gas research and development took place, and the adjacent gray wing was the “Inspection Room” where tests were conducted to check the effectiveness of the gas. These two buildings can be seen in old photographs from the time.

This is the site of the factory area that was the center of poison gas production. It was lined with buildings such as manufacturing plants for blister agents (mustard gas and lewisite), sneezing agents, and cyanide gas, as well as filling rooms, a boiler house, and repair shops. After the war, the factories were dismantled, and the area is now a plaza.