Kojindani Museum is located within Kojindani Historic Park in Hikawa-cho, Izumo City, Shimane Prefecture. Built next to the important Kojindani Ruins from the Yayoi period, the museum opened in October 2005 as a “site museum”, allowing visitors to learn about the excavated bronze artifacts, archaeological research, and the history of ancient Izumo while standing close to the actual discovery site.
The Kojindani Ruins attracted nationwide attention in 1984 when 358 bronze swords were discovered together at the site. The following year, six bronze bells and 16 bronze spearheads were also found nearby. The discovery of these three types of bronze artifacts at a single archaeological site was unprecedented in Japan and became an important turning point in the study of ancient Izumo.
All of these bronze artifacts were later designated as National Treasures of Japan. Through informative panels, videos, replicas, and life-size dioramas, Kojindani Museum presents this remarkable archaeological discovery in an accessible way. Even visitors with little knowledge of archaeology or Japanese history can enjoy learning about the mysteries and achievements of ancient Izumo.
The discovery of the Kojindani Ruins began in 1983 during an archaeological survey carried out in connection with the construction of a major agricultural road. When researchers found fragments of ancient pottery along the edge of a rice field, a full-scale excavation was launched.
In 1984, archaeologists made a remarkable discovery. Excavations revealed 358 bronze swords carefully arranged and buried on a slope in a valley. At that time, only around 300 bronze swords had been discovered in total across Japan. Finding 358 swords at one site therefore caused a major sensation in the Japanese archaeological community.
The discoveries continued in 1985. About seven meters from the location where the swords had been buried, archaeologists found six bronze bells and 16 bronze spearheads. This was the first time in Japan that bronze swords, bronze bells, and bronze spearheads had been discovered at the same archaeological site.
The artifacts were collectively designated as National Treasures in 1998 under the name “Artifacts Excavated from the Kojindani Ruins, Shimane Prefecture.” The ruins themselves were designated a National Historic Site in 1987 and have been carefully preserved as an important part of Japan’s archaeological heritage.
The museum is divided into several exhibition areas, including a permanent exhibition room, special exhibition room, temporary exhibition room, and hall exhibition space. Together, these exhibits explain the discovery of the Kojindani Ruins and introduce the history and culture of ancient Izumo.
The permanent exhibition features detailed replicas of the bronze artifacts excavated from the Kojindani Ruins. The original artifacts are owned by the Agency for Cultural Affairs and are currently preserved at the Shimane Museum of Ancient Izumo. At Kojindani Museum, visitors can examine carefully crafted replicas at close range and appreciate their forms and sophisticated workmanship.
One of the highlights is a life-size diorama recreating the way the bronze artifacts were buried. The 358 bronze swords are shown arranged neatly in four rows, giving visitors a vivid impression of what archaeologists encountered during the excavation.
The museum also introduces the techniques used to manufacture bronze swords. Video footage of casting experiments using molds made from Kimachi Stone helps visitors understand the advanced metalworking skills of people living during the Yayoi period.
The Kojindani Exhibition Room also screens “Kojindani Ruins Excavation Documentary,” which records the archaeological investigation. The footage captures the dramatic moments when bronze swords gradually emerged from the earth, as well as the surprise and excitement of the researchers.
Watching the documentary gives visitors a sense of the tension and excitement surrounding the discovery of 358 bronze swords and provides a more personal perspective on one of Japan’s most significant archaeological finds.
Every summer, the museum holds the “Kojindani Bronze Artifacts Homecoming Exhibition” to commemorate July 12, the date when the bronze swords were discovered. During this special period, the actual National Treasure artifacts, normally preserved at another museum, are brought back to the site where they were unearthed.
This provides a rare opportunity to see the original artifacts in the very area where they were discovered. Outside the homecoming exhibition period, replicas are displayed so visitors can still appreciate these remarkable ancient objects at close range.
The temporary exhibition room hosts special exhibitions focusing on the Kojindani Ruins and the history of ancient Izumo. Exhibitions introduce the latest archaeological research as well as discoveries from nearby archaeological sites, offering visitors new perspectives each time they return.
When special exhibitions are not being held, the museum presents the “Hometown of Izumo Exhibition”, featuring artifacts excavated from surrounding sites and providing a broader look at the history and culture of the Izumo region.
The entrance hall is used to display works created by local residents, including photographs, paintings, and crafts. The space serves as a place for cultural exchange and can be enjoyed free of charge, making it a welcoming area for visitors who want to experience the creativity of the local community.
The museum has a community learning room where lectures, seminars, and hands-on history programs are held. It serves as an educational center for learning about archaeology and ancient Japanese history and is used by local schools, researchers, and community groups.
When no events are taking place, the room can also be used as a rest area for visitors exploring the ruins. Large windows offer views of the greenery and seasonal scenery of Kojindani Historic Park.
The museum shop, “Izumo no Harago-ten,” sells books on archaeology and ancient history, exhibition catalogs about the Kojindani Ruins, and original museum merchandise. Visitors can also find souvenirs inspired by the ancient lotus flowers growing in the surrounding park, as well as locally made crafts and other unique items.
Kojindani Museum is surrounded by the expansive Kojindani Historic Park, covering approximately 27.5 hectares. The park includes a camellia grove and rice paddies where ancient lotus flowers are grown, offering beautiful seasonal scenery throughout the year.
In summer, approximately 50,000 ancient lotus flowers, known as Ohga lotus, bloom across the paddies. Their large pink flowers create an impressive landscape and attract many visitors. Camellias add color in spring, while autumn brings beautiful foliage, making the area ideal for walking, hiking, and enjoying nature alongside its archaeological attractions.
Kojindani Museum is relatively easy to reach from central Izumo and Izumo Airport, making it a convenient destination for travelers exploring the region.
From JR Izumoshi Station: Approximately 20 minutes by car.
From Shobara Station on the JR San’in Main Line: Approximately 5 minutes by car, or about 40 minutes on foot.
From Izumo Enmusubi Airport: Approximately 10 minutes by car.
By car: Approximately 10 minutes from the Hikawa Interchange on the San’in Expressway. The museum can also be reached via National Route 9 and the regional agricultural road known as the Izumo Roman Kaido.
Kojindani Museum was created around one of the most remarkable archaeological discoveries in Japan: the mass discovery of bronze artifacts from the Yayoi period. Through exhibitions, documentary footage, replicas, and life-size dioramas, the museum makes the history and culture of ancient Izumo easy to understand and enjoyable for visitors of all backgrounds.
The museum’s location within the expansive historic park is another attraction. Visitors can explore the archaeological site, learn about ancient Japanese culture, and enjoy the surrounding natural landscape all in one visit.
For travelers interested in Japanese history, archaeology, mythology, or the origins of the Izumo region, Kojindani Museum offers a fascinating glimpse into a world nearly 2,000 years ago. A visit here is an opportunity to experience the enduring mystery of ancient Izumo while walking through the very landscape where one of Japan’s most important archaeological discoveries was made.