The Oldest Powerhouse on the Yoshii River
The Iri Power Station Main Building (入発電所本館) is the powerhouse of a hydroelectric station built in 1920 in Iri, Kagamino Town, Tomata District, Okayama Prefecture, and was registered as a Registered Tangible Cultural Property (structure) on October 18, 2006. It is owned by the Chugoku Electric Power Company.
The Agency for Cultural Affairs records it as a single-storey wooden building with a copper roof and a building area of 189 square metres; its registration number is 33-0128.
Why It Was Registered
The Iri Power Station Main Building was registered as a building that contributes to the historic landscape of the country. The Agency for Cultural Affairs describes it as the oldest surviving powerhouse among the plants of the Yoshii River system.
According to the Agency, it stands about 30 m west of the water tank and is a single-storey timber building 15 m by 12 m under a gabled copper roof, with an office projecting to the south and a battery room to the west.
What to Look For
The roof is carried on king-post trusses, and the exterior is finished in mortar render (Agency for Cultural Affairs). A timber frame clad in mortar gives the building the look of a Taisho-era powerhouse.
From outside, note how the office and battery room project from the gabled main block. On the slope behind, the penstock runs down from the water tank between cobblestone retaining walls.
Visiting the Iri Power Station Main Building
The Iri Power Station Main Building is a utility-owned power facility and its interior is not open. Information on the station as a whole is on the Iri Power Station page. Do not enter the facility, and follow posted guidance when viewing from outside.
- 📍 Plan Your Visit to Okayama
- Find tours, activities & transport passes near Iri Power Station Main Building
- [ Kurashiki Bikan District & Korakuen Garden Tours ]
Q&A
- When was the Iri Power Station Main Building built?
- In 1920.
- When was it registered as a cultural property?
- On October 18, 2006.
- What does it look like?
- A 15 m by 12 m single-storey timber building with a gabled copper roof on king-post trusses and mortar-rendered walls.
- Why is it important?
- It is the oldest surviving powerhouse among the Yoshii River system plants.
- Can you visit it?
- The interior is not open; follow posted guidance when viewing from outside.
Basic Information
| Name | Iri Power Station Main Building (入発電所本館) |
|---|---|
| Location | 964 Iri, Kagamino Town, Tomata District, Okayama Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2006/10/18 (Heisei 18) |
| Quantity | 1 building |
| Dimensions | Wooden, single storey, copper roof, building area 189 square metres |
| Owner | Chugoku Electric Power Company |
| Public Access | Power facility (interior not open) |
References
- Iri Power Station Main Building (Database of National Cultural Properties, Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/heritage/detail/101/00005918
Last verified: 2026.10.06
