Two Phosphate Structures at West Port
The Former Toyo Sugar Phosphate Rock Storage Facility and Loading Pier (旧東洋製糖燐鉱石貯蔵庫・積荷桟橋, Kyū Tōyō Seitō Rinkōseki Chozōko and Tsumini Sanbashi) are a storage facility and a loading pier for phosphate rock, built around 1919 at West Port in Minato, Kitadaito Village, Okinawa Prefecture, and both were registered as Registered Tangible Cultural Properties on October 18, 2006.
Kitadaito is a raised coral island in the open Pacific, about 360 kilometers east of Okinawa Island. For three decades its phosphate rock was dug in the west of the island and shipped out as raw material for chemical fertilizer. These two structures handled the last steps of that chain: holding the ore, then getting it onto boats.
The storage facility sits on high ground. Its stone wall runs about 40 meters and is pierced by four reinforced-concrete tunnels, and the registered site covers 2,358 square meters. Roughly 50 meters to the west, the pier juts 18 meters out from the limestone shore in reinforced concrete. The Agency for Cultural Affairs gave them consecutive registration numbers, 47-0022 and 47-0023, and Kitadaito Village owns both.
Toyo Sugar and the Phosphate Years
Settlement of the uninhabited Daito islands began under Tamaoki Han'emon, an entrepreneur from Hachijojima. He tried mining phosphate on Kitadaito in 1910 but gave up for lack of technical know-how. In 1916 Toyo Sugar (東洋製糖, Tōyō Seitō) took over management of the islands. With the First World War cutting off imports and pushing phosphate prices up, the company drew up a mining plan and began construction in 1918; the plant was largely complete and running the following year. The Former Toyo Sugar Phosphate Rock Storage Facility and Loading Pier date from this start-up period.
The financial crisis of 1927 forced Toyo Sugar into a merger with Dai Nippon Sugar, which then ran the islands. Shipments of around 10,000 tons a year in the mid-1920s grew sharply once the Pacific War halted imports, peaking at over 70,000 tons in 1942. After the war the mine operated directly under the United States military government, but falling ore quality hurt its market, and it closed in 1950.
Most of the pits were later backfilled and turned into sugarcane fields. Following a survey of the island's mining landscape by the village board of education between 2013 and 2015, the whole production area, pits and shoreline alike, was designated a national Historic Site, the Kitadaito Island Phosphate Mine Site (北大東島燐鉱山遺跡), on February 9, 2017. The Agency's description of that site names the storage facility and the loading pier as registered properties within it.
How the Two Fit Together
Follow the ore and the layout makes sense. Rock from the pits came to West Port by light rail, drying first in the sun on open stockpile ground and then, at the port, in fired dryers. Dry ore was gathered in the storage facility, and the tunnels through its wall carried the rail tracks. For shipment the ore went by rail down to the pier, whose deck has two grooves that once held a pair of tracks. From there it was loaded onto barges.
The natural route is to stop on the slope down to West Port beneath the storage facility's wall, then continue toward the sea and view the pier from the shore. Walking downhill between them, you feel the drop the tracks once made. Other parts of the Historic Site, such as the dryer house ruins and the boat slipway, lie nearby, but these two are the registered structures.
The Toyo Sugar branch office and the employees' bathhouses in the Minato settlement are registered separately, in different years and on different lots, so this page covers only the two West Port structures.
Visiting and Getting There
The Former Toyo Sugar Phosphate Rock Storage Facility and Loading Pier are open-air ruins with no ticket office and no admission charge. Kitadaito Village lists the storage site as viewable all day with no closing days. Enquiries go to the village board of education (09802-3-4138). Because these are masonry ruins and a structure standing in the sea, plan to look from outside and do not climb onto the wall or the pier.
Ryukyu Air Commuter (RAC) flies once a day each way between Naha Airport and Kitadaito, taking about an hour; on Tuesdays, Wednesdays and Thursdays the flight stops at Minamidaito. The Daito Kaiun ferry Daito sails from Tomari Port in Naha. There is no public transport on the island, so visitors rely on rental cars, lifts from their lodging, or electric bicycles rented through the village's Jinzai Koryu Center. West Port is about 15 minutes by car from Kitadaito Airport.
West Port faces west, so late afternoon puts the sea side into backlight. To study the stonework and the pier deck, walk the site once while the sun is still high.
References
- Database of National Cultural Properties: Former Toyo Sugar Phosphate Rock Storage Facility (Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00005800
- Database of National Cultural Properties: Former Toyo Sugar Phosphate Rock Loading Pier (Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00005801
- Database of National Cultural Properties: Kitadaito Island Phosphate Mine Site (Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/bsys/maindetails/401/00003973
- Cultural Heritage Online: Kitadaito Island Phosphate Mine Site
- https://bunka.nii.ac.jp/heritages/detail/449130
- Kitadaito Village: Kitadaito Island Phosphate Mine Site (Japanese)
- https://vill.kitadaito.okinawa.jp/kankou/kanko_guide/kouzan.html
- Kitadaito Village: Access (Japanese)
- https://vill.kitadaito.okinawa.jp/kankou/access.html
- Kitadaito Tourism Navi: Access (Japanese)
- https://www.kitadaito.jp/access.html
- Kitadaito Tourism Navi: Electric Bicycle Rental (Japanese)
- https://www.kitadaito.jp/shop_detail1.html?shop_code=667
Last verified: 2026.10.06
Basic Information
| Name | Former Toyo Sugar Phosphate Rock Storage Facility and Loading Pier |
|---|---|
| Location | Okinawa Prefecture, Shimajiri District, Kitadaito Village, Minato 81-11 |
| Owner | Kitadaito Village |
| Designation | Registered Tangible Cultural Properties (2) |
| Coordinates | 25.95398, 131.28462 |
