A Mountain Shrine Hall Built against the Rock
The Kosuge Shrine Okusha Main Hall (小菅神社奥社本殿) is a shrine hall built out from a rock face of the Muromachi period in Mizuho, Iiyama City, Nagano Prefecture, and was designated an Important Cultural Property on May 26, 1964 (Agency for Cultural Affairs).
The Agency records a hall built out on posts, four bays by four, single-storey, under a hip-and-gable copper roof entered from the gable end, designated together with two shrine cabinets; designation number 01583.
The Agency record gives the Tenbun era (1532 to 1555) in its date field, while its commentary dates the building to around 1508.
A Hall in the Shelter of a Rock
The Okusha Main Hall of Kosuge Shrine is built out on posts: four bays by four, single-storey, under a hip-and-gable copper roof entered from the gable end, and designated together with two shrine cabinets (Agency for Cultural Affairs). The Agency's commentary dates it to around 1508, in the Muromachi period, and calls it a rare building tied to Shugendo, the mountain ascetic tradition.
According to Iiyama City, the hall stands in the shelter of a rock about 840 metres up the slope of Mount Kosuge. Tradition holds that En no Ozunu, the founder of Shugendo, built shrine cabinets for eight deities inside the cave in 679; a major repair is recorded in 1591. In the inner sanctuary is a spring, the Kanro pond, held to be the source of the Kosuge faith.
Why It Is an Important Cultural Property
The Agency values it as a rare building connected with Shugendo.
What to Look For
Look at how the hall is built out on posts against the rock, and the spring in the inner sanctuary (Iiyama City).
Visiting
It is owned by Kosuge Shrine (Agency for Cultural Affairs). According to Iiyama City, the approach from the third torii gate to the hall is about 1.2 kilometres, climbing between some 180 cedars and great boulders, with a steep rocky stretch just before the hall. No official information on visiting seasons was found.
Q&A
- When was the Okusha Main Hall built?
- The Agency's commentary says around 1508; its date field gives the Tenbun era.
- Where does it stand?
- In the shelter of a rock about 840 metres up Mount Kosuge (Iiyama City).
- What else is designated with it?
- Two shrine cabinets.
- How long is the approach?
- About 1.2 kilometres from the third torii gate (Iiyama City).
- When was the Kosuge Shrine Okusha Main Hall designated an Important Cultural Property?
- On May 26, 1964 (Agency for Cultural Affairs).
Basic Information
| Name | Kosuge Shrine Okusha Main Hall (小菅神社奥社本殿) |
|---|---|
| Location | Mizuho, Iiyama City, Nagano Prefecture |
| Designation | Important Cultural Property (Structure) |
| Year Designated | Designated 1964/05/26 (Showa 39) |
| Quantity | 1 building (with 2 shrine cabinets) |
| Dimensions | Built out on posts, 4 × 4 bays, single-storey, hip-and-gable, gable entrance, copper roof |
| Owner | Kosuge Shrine |
| Public Access | About 1.2 km on foot from the third torii gate (Iiyama City) |
References
- Kosuge Shrine Okusha Main Hall (Database of National Cultural Properties, Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/heritage/detail/102/962
- Conservation plan for the cultural landscape of Kosuge (Iiyama City)
- https://www.city.iiyama.nagano.jp/assets/files/gakusyushien/bunkazai/hozonkatuyoukeikaku(2).pdf
Last verified: 2026.10.23